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21.
Igor Koudriavtsev Valentin Dergachev Yury Nagovitsyn Maxim Ogurtsov Högne Jungner 《Geochronometria》2014,41(3):216-222
Radiocarbon 14C is a cosmogenic isotope, which is most extensively used by scientists from a wide variety of fields. Its rate of generation in the atmosphere depends on solar modulation and thus, studying 14C concentration in natural archives, one can reconstruct solar activity level in the past. The paper shows results of box-model calculations of generation of the 14C isotope in the atmosphere and its relative abundance during the time interval 1389–1800 AD, taking into account influence of changing climate. This interval includes the deep minimum of solar activity and period of significant change in atmospheric concentration of CO2 and global temperature. The performed analysis showed that concentration of 14C in the atmosphere reflects not only variations of the galactic cosmic rays intensity but as well changes of temperature and atmospheric CO2 concentration. It is shown that the decrease in CO2 concentration in the atmosphere during 1550–1600 can be connected with absorption of CO2 by the ocean surface layer. Thus, taking into account the climatic changes is an important condition for the reconstruction of solar activity in the past using data based on cosmogenic isotopes. 相似文献
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Alemdar Bayraktar Emin Hökelekli Temel Türker İsmet Çalik Ashraf Ashour Ayman Mosallam 《International Journal of Architectural Heritage》2019,13(4):585-599
Structural walls of old historical structures are either blind or have openings for functional requirements. It is well known that in and out of plane responses of structural walls are affected by the size, locations, and arrangements of such openings. The purpose of this investigation is to study the window opening effects on static and seismic behaviors of historical masonry old mosques. Fatih Mosque, which was converted from a church, constructed in 914 in Trabzon, Turkey, is selected for this purpose. The mosque is being restored. Structural exterior walls of the mosque were made using stone and mortar materials. When the plaster on the walls was removed during the restoration, 12 window openings were found as blind on the exterior structural walls of the mosque. Within the scope of restoration works, it is aimed to open such blind windows. In order to investigate the effects of the window openings on the structural behavior of the mosque, 3D solid and finite elements models of the mosque with and without window openings are initially developed. The experimental dynamic characteristics such as frequency, damping ratio, and mode shapes of the current situation of the mosque, where some windows openings are blind, are determined using Ambient Vibration Testing. Then, the finite element model of the current situation of the mosque is updated using the experimental dynamic characteristics. The static and seismic time history analyses of the updated finite element model with and without window openings are carried out. Structural behaviors of the mosque with and without window openings are compared considering displacement and stress propagations. 相似文献
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Hanna Dahlstrm 《Acta Archaeologica》2019,90(2):127-152
The information which can be extracted from studying craft and production in past societies is by no means limited to technology and exchange. Analysing the chaîne opératoire of iron production in medieval society provides a new perspective and knowledge of its role for urban development. Seen as a complex network of economic, social and material relations, craft and production are embedded in society and have the power to influence it. This article presents and discusses the remains of blacksmithing found at the site of Rådhuspladsen ('City Hall Square') in Copenhagen. The analysis focuses on the scale, types and organisation of the ironworking, as well as identifying the people who may have been involved, including their social and geographical networks. This study aims to better understand the role of iron production for the development of medieval Copenhagen and in general, its role in medieval Danish towns. 相似文献
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The paper offers a theory-based evaluation of the ongoing reforms in the Finnish spatial planning regime. The paper argues that Finnish planning is moving in a reactive and market-driven direction. This development is not being brought about solely through a direct decrease in public discretionary powers in planning, but is also unfolding indirectly through a process of rescaling in the spatial planning regime. These processes increase municipal autonomy in relation to other planning scales, despite problems observed in the municipality-centred market-driven planning orientation. The resulting reduction in manoeuvring room in public planning is conceptualized in the paper as expanding vacuums of strategic planning. Building on concepts from the literature on state transformation theory and scale theory, the paper draws together theoretical and empirical conclusions from several case studies conducted in close-to-administration projects. 相似文献
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ABSTRACTRecent scholarly work has enhanced our understanding of how new path development activities are enabled or constrained by ‘regional environments’, made up of pre-existing industrial structures, knowledge organizations, support structures and institutional configurations. This paper moves beyond overly static views on regional environments. We develop a dynamic perspective by analysing conceptually and empirically how a constraining environment can be transformed into one that enables the development of new growth paths. The paper offers a typology of various modes of change, including layering, adaptation and novel application that are used by key actors to ‘manipulate’ the regional support structures to facilitate new regional industrial path development. The conceptual framework is applied to a case study of the digital games industry in the region of Scania, southern Sweden. Our findings suggest that the creation of a more enabling environment for the growth of the digital games industry has been the outcome of multi-scalar processes and combinations of various modes of change employed by a few key individuals operating in the newly emerging path. 相似文献
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Stephanie Döpper 《Arabian Archaeology and Epigraphy》2017,28(2):190-208
A third‐millennium BC tomb was subject to a rescue excavation in connection with the construction of a new road near the village of Al‐Khubayb in the Sultanate of Oman. It yielded a small number of finds, especially small metal objects that belonged to a later reuse of the tomb in the Samad period. As all diagnostic finds from the tomb date to the reuse, its architectural elements were the only indicator for the construction date of the tomb. Besides its small size and large wall thickness, which might suggest that the tomb is a transitional type between the Hafit and the Umm an‐Nar periods, its separation into two chambers and its facade made of white, dressed stones, can be seen as a clue for a construction date of the tomb in the Umm an‐Nar period. 相似文献
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