共查询到20条相似文献,搜索用时 15 毫秒
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ABSTRACT. The frequency of occurrence of the different types of solutions to the Weber problem is studied. These solutions are: a location at an attraction point due to a dominant force, to incompatible angles, or to concavity; a location at infinity; a location inside the polygon; and a location outside the polygon. Situations involving both attraction and repulsion points are examined in the triangle and in the more-than-three-sided polygon context, and methods for solving the corresponding problems are compared. A trigonometric solution is proposed for the triangle case involving one repulsion and two attraction points. The variation in the frequency of a location at an attraction point when the number of attraction points increases while the number of repulsion points remains the same is observed as well. Implications of the results are studied for the analysis of dynamic location processes. 相似文献
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ABSTRACT. In this paper we attempt to clarify the theoretical links between the concepts of “center of gravity” and “point of maximum population density” which describe the present, and the concepts of “minimum of the comprehensive Weber problem” and “maximum comprehensive gravity potential” which guide the future. Critical values of the characteristic parameters of the relevant functions are estimated. Implications for the understanding of spatial inertia are discussed. 相似文献
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Pey-Chun Chen Pierre Hansen Brigitte Jaumard Hoang Tuy 《Journal of regional science》1992,32(4):467-486
ABSTRACT. Weber's problem consists of locating a facility in the plane in such a way that the weighted sum of Euclidean distances to n given points be minimum. The case where some weights are positive and some are negative is shown to be a d.-c. program (i.e., a global optimization problem with both the objective function and constraint functions written as differences of convex functions), reducible to a problem of concave minimization over a convex set. The reduced problem is then solved by outer-approximation and vertex enumeration. Moreover, locational constraints can be taken into account by combining the previous algorithm with an enumerative procedure on the set of feasible regions. Finally, the algorithm is extended to solve the case where obnoxiousness of the facility is assumed to have exponential decay. Computational experience with n up to 1000 is described. 相似文献
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CHRISTOPHER PARE 《Oxford Journal of Archaeology》1987,6(1):43-61
Summary. A technological advance in wheel construction, entailing spokes with thickened or strengthened ends, can be detected in Central Europe at the start of the Late Bronze Age. Spokes with thickened ends are seen in Central Europe on full-size wheels, wagon models and wheel depictions. It is argued that this technological innovation had its source in the Aegean, where wheels with thickened spokes are seen not only depicted on late Mycenaean craters but also on Linear B wheel ideograms. The second part of the article discusses a closely-related Central European group of wheel-shaped designs, characterised by forked spokes, found on pin-heads, pendants, decorated belt-sheets, phalerae and belt-hooks. As some of these designs refer to real wheels constructed with thickened or strengthened spoke ends, it is concluded that the designs really represent wheels, although the designs are often so simplified that this is not immediately apparent. 相似文献
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This paper argues for cross-validation to reduce bias in estimating Mahalanobis distances of individuals to groups, a particular problem with small sample sizes. Formulae for the efficient computation of cross-validated distances, which avoid excessive matrix inversion, are given. The use of Mahalanobis distances as measures of consistency, or as indications of outlying values, is described. The little-known technique of gamma plotting is outlined and discussed as an aid to interpreting distances in these terms. Both cross-validation and gamma plotting are illustrated in an example on marble composition. 相似文献
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品牌差异化定位是目的地获取竞争优势的重要手段,当前由于目的地旅游资源同质化,导致了目的地品牌形象趋同、竞争力下降等问题。针对此,本研究试图借鉴品牌个性理论找到目的地差异化定位的新视角。文章选取周庄、乌镇和西塘三个资源禀赋相同的目的地为研究对象,通过分析到访旅游者撰写的游记发现,虽然旅游者对不同目的地的感知形象相似,但是感知个性存在明显差异。其中,乌镇的个性集中表现为"雅";周庄"智"的个性最突出;西塘则在"乐"上有更好表现。基于此,本文为三个目的地提供了个性导向的品牌定位建议。研究表明在品牌形象趋同的情况下,资源同质旅游目的地仍可借助趋异的品牌个性进行差异化定位,并使品牌获得持久的竞争力。 相似文献
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Michael M. Harmon 《政策研究杂志》1980,9(4):559-567
This paper elaborates a “personal,” as opposed to an institutional, view of administrative responsibility. The idea of personal responsibility is better suited for appreciating the cognitive, conceptual, and interpersonal dynamics of policy processes than is the institutional view of responsibility as accountability. From the perspective of personal responsibility, the primary impediment to responsible action by policy makers, policy analysts, and administrators is not that they may act in ways that are ethically or morally wrong. Rather, the problem is that such actors may either not perceive that important choices are available to them or, when choices are perceived, their moral, as opposed to their instrumental, content may not be appreciated. Responsible action should thus be seen as a conceptual or cognitive issue, not simply one of adherence to or departure from institutionally objectivated standards of correctness. Inability to appreciate the moral nature of action may be explained by the cognitive tendency to reify policy making and administrative institutions, roles, rules, and situations. 相似文献
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This article argues that realist invocations of Weber rely on an unrealistic reading of Weber's realism. In order to escape the allure of Weber's dramatic posture of crisis, we place his seminal lecture on “Politics as a Vocation” (1919) in its historical and philosophical context of a revolutionary conjuncture of dramatic proportions, compounded by a broader crisis of historicism. Weber's rhetoric, we argue, carries with it not only the emotion of crisis but is also the expression of a deeper intellectual impasse. The fatalistic despair of his position had already been detected by some of his closest contemporaries for whom Weber did not appear as a door‐opener to a historically situated theory of political action but as a telling and intriguing impasse. Although the disastrous history of interwar Europe seems to confirm Weber's bleakest predictions, it would be perverse to elevate contingent failure to the level of retrospective vindication. 相似文献
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胁迫视角下乡村旅游地文化影响研究进展与框架构建 总被引:1,自引:0,他引:1
乡村文化的保护和发展不仅是新时期我国乡村振兴的重要课题,也是乡村旅游可持续发展的关键所在。旅游开发在带来乡村经济振兴的同时,更多的是胁迫乡村文化生态系统发生变化、产生反应或功能失调,进而导致乡村文化的受损甚至消亡。通过国内外乡村旅游地文化影响相关文献的梳理归纳和研究评述,本文发现当前研究缺乏基于文化胁迫视角的理论框架、文化影响的系统性研究及量化表达薄弱。在系统回顾胁迫生态理论的科学内涵和发展趋势的基础上,指出其应用在乡村旅游人地关系研究中的重要意义,进而提出旅游开发对乡村文化的胁迫模型和胁迫视角下乡村旅游地文化影响研究亟需解决的核心问题。最后从时间-空间-社会维度出发,构建旅游开发对乡村文化胁迫研究的理论框架和内容体系,以期为快速城镇化和旅游发展背景下的乡村振兴、乡村文化保护和乡村旅游可持续发展提供理论参考。 相似文献