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Research on complex systems has identified various aggregate relationships in phenomena that describe these systems. Travel length has been characterized by negative power distributions. Controversy, however, exists over whether mobility patterns can be modeled in terms of a simple power law (Lévy flight model) or that more complicated power laws (exponential power law, truncated Pareto) are required. This study concentrates on two issues: testing the validity of exponential power laws and truncated Pareto distributions in urban systems to describe aggregate mobility patterns, and examining differences in mobility patterns for different travel purposes. The article describes the results of an analysis of Global Positioning System (GPS) taxi trajectory data, collected in Guangzhou, China, to identify mobility patterns in the city. The least squares statistic is used to estimate the parameters of the distribution functions. Results suggest that a fusion of functions, based on an exponential power law and a truncated Pareto distribution, represents the travel time distribution best. Moreover, the findings of this study indicate different mobility patterns to exist for different travel purposes. 相似文献
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Based on William Morris Davis’ great Transcontinental Excursion of 1912, this article assesses and reviews the Geography by Rail® program (GbR) – a unique, short-term, field-based study abroad experience that takes an uncommon-in-the-US approach to international exploration and fieldwork, incorporating on-the-ground, regional geography-based learning experiences. Though it could be used as such, this is not intended as a “how-to” article, but instead, an examination of how the program’s alternative approach to short-term, field-based learning increases student engagement, enlivens the discipline of geography by championing the regional geography approach, and bridges the physical-human divide in geography. Examples are given of assessment techniques, relevant skills gained by student participants, student feedback received, and potential limitations of such a program. Our main goal rests in demonstrating that by being in the landscape, practicing in it, students often gain a perspective not achievable in the traditional classroom setting. In the regional and romantic geography sense, favoring breadth of learning over depth, we further argue that GbR represents a novel way to accomplish this important-yet-not-often-fostered and, oddly and unfortunately, difficult-to-find-in-geography concept. 相似文献
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Excavations at the site of Langley’s Lane, Bath and North-East Somerset, have revealed an important sequence of Late Mesolithic activity focused around an active tufa spring. The sequence of activity starts off as an aurochs kill and primary butchery site. Culturally appropriate depositional practices occur through the placement of a selection of bone in the wetland of the spring and the digging of pits around the spring margins. The spring at Langley’s Lane continued to be visited and more animal bone and lithic material was placed in the wetland. Finally, visits to the site involved yet more formalized activity in the form of pit digging and the creation of a stone surface. Activities such as these are difficult to locate in the archaeological record and Mesolithic ritual activity rare, making this a site of some significance to studies of Mesolithic NW Europe. 相似文献
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