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51.
In this study, we relax one of the general assumptions in the hub location literature by allowing routed flows between nonhub nodes. In hub networks, different flows are consolidated and routed via collection, interhub, and distribution arcs. Due to consolidation, some flows travel long paths despite closeness of their origin and destination. In this study, we allow direct flows by penalizing by a scalar factor of original cost of transshipment between these arcs. We present mathematical models for median, center, and set covering versions of the problem for single‐ and multi‐allocation cases. We test the models with the CAB and TR data sets. We discuss the properties of established direct connections for different models by using another mathematical model where the number of direct flows is bounded and interpret the effect of changes in problem parameters. 相似文献
52.
The study analysed pre-Hispanic gold objects found within a surprising archaeological finding of a structure that likely served as a funeral pyre in Medellín, Colombia. 14C analyses of the site's organic materials dated the structure to the fifth century ce . The metal objects were subjected to X-ray diffraction (XRD), energy-dispersive X-ray fluorescence (EDXRF), scanning electron microscopy-energy dispersive X-ray (SEM-EDX), density measurement by the Archimedes method, and metallographic analysis. The measurements by EDXRF and SEM-EDX showed that the pieces were composed mostly gold and silver. The XRD results indicated that the microstructure of the objects corresponded to a single phase of gold and silver. The images obtained by the metallographic microscope showed equiaxial grains with some twins, a structure consistent with annealed metals. The different colours observed correspond to different grain orientations. Pre-Hispanic objects from a second archaeological site in the municipality of Amalfi (Department of Antioquia) were also analysed for comparative purposes. The results showed that the gold objects were not subjected to any alloying process, but were instead manipulated in their original form (native gold). The shape of the objects and their microstructural results suggested that the pieces were manufactured by casting, mechanical deformation and then annealing. 相似文献
53.
Five unidentifiable, completely corroded ancient coins (three of which were large fragments), proven to lack any residual internal metal, were scanned by nano-computed tomography (CT) to see if discernible detail might still be present. One fragment could be identified as an early fourth-century Urbs Roma commemorative AE 3/4. Another fragment was a coin of either Valerian or of the joint rule of Valerian and Gallienus, which could be dated to the period 254–56 ce . The other three lacked discernible detail. This proof-of-concept study shows that nano-CT scanning has the potential to allow non-invasive identification of at least some totally corroded coins. 相似文献
54.
The study analyses the chemical composition of 57 glass samples from 40 beads discovered at 20 archaeological sites in Poland. The beads are dated to Hallstatt C–Early La Tène periods (c.800/750–260/250 bce ). Analyses were carried out using laser ablation-inductively coupled plasma-mass spectrometry (LA-ICP-MS). Two groups were distinguished among the glasses based on the MgO/K2O ratio: high-magnesium glass (HMG), five samples; and low-magnesium glass (LMG), 52 samples. The former were melted with halophyte plant ash, the second with mineral soda. These glasses were produced in the Eastern Mediterranean (more likely in Mesopotamia or Syro-Palestine than in Egypt) and transported in the form of semi-products to secondary glass workshops in Europe. Some of the white opaque glass was coloured and opacified in Europe. 相似文献
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56.
The Te Kawa a Māui Atlas project explores how mapping activities support undergraduate student engagement and learning in Māori studies. This article describes two specific assignments, which used online mapping allowing students to engage with the work of their peers. By analysing student evaluations of these activities, we identify four aspects that benefit student engagement: mapping diversifies the learning experience; mapping promotes acquisition of a different skill set; online mapping allowed more open sharing of work and; mapping promotes place-based learning. Some students were ambivalent about the assignments, so mapping should only be used to support other learning objectives. 相似文献
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Negotiations of Irish identity in the wake of terrorism: the case of the Irish in Birmingham 1973–74
Sarah O’Brien 《Irish Studies Review》2017,25(3):372-394
This article explores the Irish migrant experience in Birmingham during and in the wake of terrorist campaigns carried out in Britain between 1969 and 1975 and attributed to the Irish Republican Army (IRA). Beginning with a discussion of the competencies with which Irishness was associated at the close of the 1960s in England, many of which were hinged on a notion of the Irish predisposition towards violence, the article continues on to take the political, cultural and religious “temperature” of the Irish community in Birmingham between 1969 and 1975, and follows on with a discussion of the specific strategies sought out by Irish immigrants to come to terms with the effect of events such as the “Birmingham Bombings” on their daily lives. Principle findings that emerge from the study indicate that IRA terrorism forced the Irish in Birmingham to engage with and adopt a number of distinct linguistic and cultural strategies in the post-1974 period, the cultivation of which indefinitely altered their relationship with Ireland as “home”, their visibility in the public British sphere and their associational patterns and practices within the migrant enclave. 相似文献
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A Rock‐Magnetic Quest for Possible Ore Sources for the Ancient Iron‐Smelting Industry in the Olkhon Region (Lake Baikal,Siberia)
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G. G. Matasova A. Yu. Kazansky N. O. Kozhevnikov S. V. Snpokov A. V. Kharinsky 《Archaeometry》2017,59(3):511-527
Rock‐magnetic techniques were used to examine the topsoil layer of Kurma archaeological site (in the Olkhon region, on the north‐western coast of Lake Baikal, Siberia) in an effort to determine the possible sources of iron ores for iron‐smelting centres (at about the bc /ad boundary). Measurements have shown a magnetic enhancement of the topsoil due to magnetite grains resulting from weathering of strongly magnetic crystalline rocks. They have also revealed a preliminary picture of the distribution of strongly magnetic topsoils around the ancient iron‐smelting centres. Perhaps, in addition to traditional sources of raw materials, the ancient metallurgists used black sand talus as an ore deposit. 相似文献