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The location set-covering problem (LSCP) and the maximal covering location problem (MCLP) have been the subject of considerable interest. As originally defined, both problems allowed facility placement only at nodes. This paper deals with both problems for the case when facility placement is allowed anywhere on the network. Two theorems are presented that show that when facility placement is unrestricted, for either the LSCP or MCLP at least one optimal solution exists that is composed entirely of points belonging to a finite set of points called the network intersect point set (NIPS). Optimal solution approaches to the unrestricted site LSCP and MCLP problems that utilize the NIPS and previously developed solution methodologies are presented. Example solutions show that considerable improvement in the amount of coverage or the number of facilities needed to insure total coverage can be achieved by allowing facility placement along arcs of the network. In addition, extensions to the arc-covering model and the ambulance-hospital model of ReVelle, Toregas, and Falkson are developed and solved.  相似文献   
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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.  相似文献   
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An Iron Age timber settlement which, in view of the defensive structures uncovered, is described as a lake fortress, on an island in Lake ārai?i, north-eastern Latvia, was excavated in 1965–69 and 1975–79 by teams led by Jānis Apals, who distinguished five construction phases. Dendrochronological analysis produced a c. 100-year floating chronology for Norway spruce (Picea abies (L.) Karst.) timbers from the earliest phase. A 14C wiggle-match was undertaken to obtain an absolute date range for the final year of the floating chronology, and thus for the construction of the settlement. Ten blocks of wood from one timber, each comprising 6-11 years and collectively spanning the whole 93-year tree-ring series, were dated by AMS. Using the IntCal13 calibration data, there is a 95% probability that the felling date of this timber falls in the range 775–784 cal AD. It appears, however, that the AD 775 spike in the atmospheric 14C level occurred within the 6-year span of the last sample. On this basis, we can narrow the date of construction to 776–780 cal AD. This date is significantly earlier than those reported in previous publications.  相似文献   
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An intact Bell Beaker grave was discovered in February 1996 at Wellington Quarry, Marden, Herefordshire. The unmarked flat grave had no signs of a ditch or barrow, but may have been timber lined. It contained a tanged copper knife, a shale wristguard fragment, four barbed and tanged arrowheads, three arrowhead blanks, three flint knives, two triangular points or small daggers and four flint flakes. The adult male inhumation was accompanied by a complete, Maritime (AOO) Bell Beaker and may be dated to 2750–2500 BC (Late Neolithic). It belongs to Case's Group D. A notable feature of the grave goods is their different states of wear and completeness, varying from pristine to old, and including a fragment of a wristguard.  相似文献   
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Abstract: Our goal in this paper is to identify how recent escalations in immigration enforcement and changes in migration practices affect the ability of the state to continue to serve two of its key “productive” functions: protecting capital accumulation within industry and ensuring the state's own political legitimacy in the eyes of the public. We draw on our ethnographic research on Latino migrant dairy farm workers in Wisconsin to examine the ways in which a group of migrant workers experiences the process of being enforced as “illegal” bodies. We find that migrant dairy workers’ palpable sense of “deportability” articulates with the specific structure of dairy work in ways that make the economically and politically “ideal” migrant: compliant at work and invisible otherwise.  相似文献   
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