The valley problem in bottomside ionogram analysis

The use of ordinary and extraordinary ray vitrual height data to estimate valley parameters is studied using a least-squares single-polynomial analysis. For any assumed valley depth this technique enables direct determination of the best-fitting valley ‘width’ and F-region real-height profile. Tests on model profiles show that the method can satisfy the virtual height data, to within normal experimental error, over a considerable range of assumed depths. Thus iteration of valley depth to achieve best agreement with the virtual height data is unsound in the presence of typical scaling uncertainties: there is insufficient information in a standard ionogram to provide useful estimates of both valley width and valley depth. A sample of 130 daytime ionograms have been analysed assuming a zero-depth valley. The resulting valley widths were generally between 0 and 25 km with an average of 11 km.     

A synthesised trough ionogram

The simulations of trough ionograms by Lobb and Titheridge (1977) are supplemented by calculating a trace caused by rays having a double oblique reflection in the ionosphere and not retracing their paths. It is also shown how the different parts of the traces are caused by echoes of different types.     

Comparison of analytical techniques for analysis of archaeological bronze

While many analyses of archaeological bronzes have been reported in the literature, in practice it is very difficult to compare them. To assess the present status of the chemical analysis of bronze two ancient objects—a flat axe (arsenic bronze) and a sickle (tin bronze)—were cut into pieces weighing about 2 g each and were distributed to 11 laboratories. The participants used the following methods for analysis: INAA, ED–XRF, PIXE, TRXRF, FAAS, ICP–AES, ICP–MS, SEM–EDS, LA–ICP–MS and PGAA. The samples were analysed in at least quadruplicate. Dixon's and Iglewicz and Hoaglin's tests were used to detect outliers. The majority of methods provided comparable results, especially for macroelements, independent of the technique and standards used. The number of determined elements depended on the method and, naturally, on the concentration level. Therefore an important recommendation that can be made is to supply, with each archaeometric investigation, data from the analysis of appropriate Certified Reference Materials (CRMs) used in the study.     

古陶瓷元素成分分析技术定量方法的探讨

随着古陶瓷科学技术分析研究的不断深入,不同分析技术间数据的交流和借鉴成为必然。本工作主要从技术角度分析目前国内用于古陶瓷分析研究常见的几种科学分析技术的测量偏差来源,并对测量分析中的相关问题进行了探讨。在针对古陶瓷样品不均匀性要求方面,比较了几种分析技术实验条件的选择,指出适合于古陶瓷分析测量束斑的大小为φ2-3mm。结合上博实验室ED-XRF技术用于古陶瓷胎样品定量分析方法工作,详尽探讨了古陶瓷胎样品的原始样和粉末压片样的定量分析,指出古陶瓷中的“气孔效应”是造成两类样品不能公用标准样品的原因。     

基于SBAS-InSAR技术的庆阳北石窟寺区域稳定性监测与分析

区域稳定性监测是石窟寺长期保护的一项重要措施。本研究以庆阳北石窟寺所在区域为对象,基于2019年的15景Sentinel-1A卫星雷达影像,采用小基线集合成孔径雷达干涉测量(SBAS-InSAR)技术对研究区稳定性进行监测,获取了研究区雷达视线向形变速率及时序形变,分析了研究区形变的空间、时间分布规律及其原因。监测结果表明:北石窟寺所赋存的覆钟山山体整体稳定,存在微小形变,不存在潜在滑坡变形特征;研究区主要形变区沿河分布,蒲、茹两河交汇处形变最为明显;研究区时序形变呈现随季节变化的规律性,造成其规律性的原因为随季节变化的土壤侵蚀和董志塬固沟保塬项目的实施。该研究证明了InSAR技术在文物遗址区域稳定性监测的可行性,以及其在具有长期性、可靠性的优势,为石窟寺遗址长期预防性保护提供了新的思路和方法。     

辅料染色技术在古代纺织品保护修复中的应用

在国外,染色技术是纺织品保护修复人员必须掌握的一门专项技术,但目前于国内却很少得到应用。本文主要介绍染色技术在纺织品保护修复中的适用范围,如用于背衬或覆护辅料的染色、缝线染色等和实验室常用的染色方法,这将有助于引起国内纺织品保护修复领域对此项实用技术的关注和推广。     

The application of forensic fire investigation techniques in the archaeological record

This paper seeks to assist in defining a role for a suite of adapted techniques of analysis and interpretation that are drawn primarily from the methods of contemporary forensic fire investigation. In so doing, the paper identifies a general paucity of literature providing detailed discussions of structural fires preserved in the archaeological record. In addition the paper provides a generalised account of the manner in which structural fires (most especially compartment fires, defined later) will tend to burn and which tools can assist in the interpretation of fire dynamics, the identification of points of origin of fire within buildings, and the response of building materials to burning. Ultimately, such an approach can improve understanding of past structures, and also provide an interpretative avenue for understanding human response to fire and the risk of structural fire in the past.     

The effect of vertical drift on the equatorial F-region stability

Owing to the high conductivity along magnetic field lines, the stability of the night-time equatorial F-region is determined by magnetic field line integrated quantities. However, slow vertical diffusion near the magnetic equator plus the rapid increase in ion chemistry rates at lower altitude combine to give a very small positive scale height for the electron concentration on the bottomside of the region. As a result, the field line averaged quantities are reasonably approximated by their equatorial values, provided that the E-region does not contribute significantly. The time-dependent behavior of the growth rate for the Rayleigh-Taylor gravitational instability on the F-region bottomside is examined here as a function of the vertical E × B drift velocity using reasonable chemistry to obtain approximate equatorial vertical profiles of ionospheric parameters. It is found that the growth rate exceeds the chemical recombination rate over most of the bottomside F-layer even without vertical drift, but that a realistic E × B drift can result, after about 1 h, in an increase of this growth rate by an order of magnitude. The absolute growth rate is so small (< 10⁻³ s⁻¹) with zero vertical drift that a seeding mechanism would probably be required for the formation of bubbles. The rapid appearance of bubbles shortly after sunset appears likely only after a period of upward drift, as is observed.     

青海瞿昙寺瞿昙殿壁画制作材料与工艺初步分析

青海瞿昙寺是中原地区至今保存较完整,集古建、雕刻彩绘和壁画于一体的明代早期官式建筑群。瞿昙寺瞿昙殿现存壁画约217.5 m²,是中原地区经典的明代早期藏传佛教壁画,具有珍贵的历史和学术研究价值。本研究通过显微镜(OM)、剖面分析(Cross-section)、扫描电镜-能谱(SEM-EDS)、X射线衍射(XRD)等多种分析方法,对瞿昙寺瞿昙殿壁画制作材料及工艺开展了初步调查分析。结果显示:瞿昙殿壁画以砖墙体为支撑体,地仗层由粗泥层和细泥层组成;地仗中粗细泥层含沙量不等,粗泥层含沙量约60%,细泥层含沙量较少,约为16%～25%;地仗层中总体纤维含量为3%左右;地仗土粒度级配良好,粒径多集中在1~100 μm之间;地仗中含少量硫酸钠和氯化钠;瞿昙殿壁画使用颜料主要为铅丹、朱砂、氯铜矿、副氯铜矿、石青等矿物颜料,颜料层厚度20～200 μm之间;铅丹颜料在瞿昙殿中出现“章丹打底银朱盖面”的分层应用以及铅丹变色的现象;瞿昙殿壁画中明代壁画无底色层,清代乾隆时期壁画有底色层。本次分析研究获得瞿昙殿壁画层位、地仗组成和颜料使用信息,为瞿昙殿壁画科学保护和深入研究提供重要的第一手资料。     

龙门石窟奉先寺的红外成像监测与分析——基于MATLAB图像处理技术

龙门石窟奉先寺的安全长期受到风化及渗水等病害影响。针对奉先寺石造像阿难头部区域及卢舍那大佛南侧渗水区域,利用红外成像设备对该区域进行为期一年的实时监测,并借助MATLAB语言的图像处理技术对大量红外图像进行数据分析。结果发现佛像头部裂隙处存在温差引起的循环热应力,该温差主要由灌浆加固区域和岩体本体之间热传导性能差异导致,且晴天上午前后的温差应力变化最显著;归纳了监测期间降雨和渗水发生的时间规律,统计得出了不同区域渗水程度的差异。将红外成像和大数据分析结合应用于石窟预防性保护中,实现了对病害同时进行图像监测和统计评估,为其他石窟寺的监测与数据分析工作提供参考。     

New paleoparasitological techniques

Ruffer was the first researcher to show, using hydration of samples and histological techniques, the presence of Schistosoma haematobium eggs in the kidneys of Egyptian mummies dating between 1250 BC and 1000 BC. Since then, with the collaboration of archaeologists, palynologists, parasitologists, biologists, entomologists, ecologists, malacologists…new ideas have arisen and different techniques have been adapted for the study of parasites in an archaeological context. Research into the hydration of samples has been carried out, and flotation and sedimentation techniques started to be used, testing different solutions. Eggs, larvae and adults of both ecto- and endoparasites, as well as non-parasitic arthropods have been found, but none of the methods used have enabled to quantify the parasitic forms found, which is important to know the epidemiology of parasitic diseases and to carry out comparative studies. At present, the development of molecular biology techniques applied to palaeoparasitology is permitting the detection of traces of parasites in the past.     

Ultrathin sectioning techniques

Epoxy mixtures incorporating Araldite available in Australia have been used to embed Recent organisms, fossils and sedimentary rocks. Resultant sections of embedded material may be less than 10 micrometres thick and give increased resolution of fine structures. Mixtures used and sectioning techniques are described.     

从9种核心期刊的文献计量分析看核技术在文物保护与考古中的应用

从9种核心期刊的文献计量统计分析入手,分析了不同期刊、不同具体核技术方法、不同年份核技术应用文献量的差别,研究了差别的原因.介绍了主要核技术具体方法的含义和在考古及文物保护工作中的作用.分析和数据表明,核技术在考古和文物保护领域更广泛地应用及提高年代测量精度是核技术应用的两个发展方向.     

Evaluation of underwater surveying techniques

The paper discusses the application of a number of manual trilateration surveying systems, an acoustic surveying system and a photogrammetric system applied to a rigid test frame. Results and relative merits are compared and discussed.     

Advocacy coalitions,beliefs, and learning: An analysis of stability,change, and reinforcement

Policy processes are ongoing phenomena without beginning or end. Accordingly, a major focus of research has been on questions of stability and change. This paper continues in this tradition by examining advocacy coalition stability, belief change, and learning. This paper draws on three waves of policy actor surveys that compare panel and non-panel samples. The data were collected in 2013, 2015, and 2017 in the context of oil and gas development in Colorado, USA. The findings mostly confirm that coalitions and beliefs tend to be stable and that learning leans toward reinforcement rather than change in beliefs. However, although rare, some instances of belief change, change in coalition membership, and changing policy positions occur. This paper makes theoretical and empirical contributions to the study of stability, change, and reinforcement of advocacy coalitions and their beliefs and charges policy scholars to look more at the exceptions to the evidence rather than the confirmations.     

The Roman quarries at Antinoopolis (Egypt): development and techniques

The aim of this research was the survey and the study of the many quarries located in the first spurs of the Gebel el-’Adila, close to Antinoopolis (Middle Egypt). These quarries are an excellent opportunity for observation and research concerning the “landscape archives” and preserve traces of man’s activity, representing a real cultural heritage. The paper gives a short geological setting of the area and reports our recent study (2006 onward) on traces, typologies, methods and development of the quarrying activity in the area, focussing on the Roman period. The working traces allowed us to define the working tools used for quarrying, the organisation of the works and of the quarry exploitation, as in the area many remains of the quarry organisation network are extant or recognisable, such as: service posts, sledge-ways, docks.