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Jia, Tao
Publications (6 of 6) Show all publications
Jiang, B., Liu, X. & Jia, T. (2013). Scaling of Geographic space as a universal rule for map generalization. Annals of the Association of American Geographers, 103(4), 844-855
Open this publication in new window or tab >>Scaling of Geographic space as a universal rule for map generalization
2013 (English)In: Annals of the Association of American Geographers, ISSN 0004-5608, E-ISSN 1467-8306, Vol. 103, no 4, p. 844-855Article in journal (Refereed) Published
Abstract [en]

Map generalization is a process of producing maps at different levels of detail by retaining essential properties of the underlying geographic space. In this paper, we explore how the map generalization process can be guided by the underlying scaling of geographic space. The scaling of geographic space refers to the fact that in a geographic space small things are far more common than large ones. In the corresponding rank-size distribution, this scaling property is characterized by a heavy tailed distribution such as a power law, lognormal, or exponential function. In essence, any heavy tailed distribution consists of the head of the distribution (with a low percentage of vital or large things) and the tail of the distribution (with a high percentage of trivial or small things). Importantly, the low and high percentages constitute an imbalanced contrast, e.g., 20 versus 80. We suggest that map generalization is to retain the objects in the head and to eliminate or aggregate those in the tail. We applied this selection rule or principle to three generalization experiments, and found that the scaling of geographic space indeed underlies map generalization. We further relate the universal rule to T\"opfer's radical law (or trained cartographers' decision making in general), and illustrate several advantages of the universal rule. Keywords: Head/tail division rule, head/tail breaks, heavy tailed distributions, power law, and principles of selection

Keywords
Heavy tailed distributions, power law, principles of selection, head/tail division, head/tail breaks
National Category
Computer and Information Sciences
Identifiers
urn:nbn:se:hig:diva-15231 (URN)10.1080/00045608.2013.765773 (DOI)000320300300006 ()2-s2.0-84879543275 (Scopus ID)
Available from: 2013-09-13 Created: 2013-09-13 Last updated: 2018-03-13Bibliographically approved
Jia, T., Carling, K. & Håkansson, J. (2013). Trips and their CO2 emissions to and from a shopping center. Journal of Transport Geography, 33, 135-145
Open this publication in new window or tab >>Trips and their CO2 emissions to and from a shopping center
2013 (English)In: Journal of Transport Geography, ISSN 0966-6923, E-ISSN 1873-1236, Vol. 33, p. 135-145Article in journal (Refereed) Published
Abstract [en]

Previous studies have focused on entire trips within a geographical region, while only a few have examined trips to and from a city landmark. This paper examines trips and their CO2 emissions to and from a shopping center from a time-space perspective, and it further considers how this information can be used in relocation planning. It is a case study in the Borlange city in mid-Sweden where trips to the city's largest shopping mall are scrutinized. We use GPS tracking data of car trips starting and ending at the shopping center. Firstly, we analyze the traffic emission patterns from a time-space perspective where the temporal patterns reveal hourly-based traffic emission dynamics. The spatial analysis uncovers a heterogeneous distribution of traffic emissions in spatial areas and individual street segments. Secondly, we find the observed trips mostly agree with an optimal route in terms of CO2 emissions. Drawing on this finding, we thirdly evaluate the location of the current shopping center by comparing it to two competing locations. We conclude that the two competing locations, being in the vicinity of the current one, would induce an insignificant improvement in terms of CO2 emissions. (C) 2013 Elsevier Ltd. All rights reserved.

Keywords
GPS tracking data, Trips, CO2 emissions, Relocation planning
National Category
Civil Engineering
Identifiers
urn:nbn:se:hig:diva-17816 (URN)10.1016/j.jtrangeo.2013.09.018 (DOI)000330817000013 ()2-s2.0-84886291768 (Scopus ID)
Available from: 2014-11-08 Created: 2014-11-08 Last updated: 2018-03-13Bibliographically approved
Jia, T., Jiang, B., Carling, K., Bolin, M. & Ban, Y. (2012). An empirical study on human mobility and its agent-based modeling. Journal of Statistical Mechanics: Theory and Experiment (11), P11024
Open this publication in new window or tab >>An empirical study on human mobility and its agent-based modeling
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2012 (English)In: Journal of Statistical Mechanics: Theory and Experiment, ISSN 1742-5468, E-ISSN 1742-5468, no 11, p. P11024-Article in journal (Refereed) Published
Abstract [en]

This paper aims to analyze the GPS traces of 258 volunteers in order to obtain a better understanding of both the human mobility patterns and the mechanism. We report the regular and scaling properties of human mobility for several aspects, and importantly we identify its Levy flight characteristic, which is consistent with those from previous studies. We further assume two factors that may govern the Levy flight property: (1) the scaling and hierarchical properties of the purpose clusters which serve as the underlying spatial structure, and (2) the individual preferential behaviors. To verify the assumptions, we implement an agent-based model with the two factors, and the simulated results do indeed capture the same Levy flight pattern as is observed. In order to enable the model to reproduce more mobility patterns, we add to the model a third factor: the jumping factor, which is the probability that one person may cancel their regular mobility schedule and explore a random place. With this factor, our model can cover a relatively wide range of human mobility patterns with scaling exponent values from 1.55 to 2.05.

Place, publisher, year, edition, pages
Bristol: Institute of Physics Publishing (IOPP), 2012
Keywords
interacting agent models, scaling in socio-economic systems, stochastic processes
National Category
Civil Engineering Mathematics
Identifiers
urn:nbn:se:hig:diva-17867 (URN)10.1088/1742-5468/2012/11/P11024 (DOI)000312102500002 ()2-s2.0-84871242406 (Scopus ID)
Funder
Swedish Retail and Wholesale Development Council
Available from: 2014-11-09 Created: 2014-11-09 Last updated: 2018-03-13Bibliographically approved
Jia, T. & Jiang, B. (2012). Exploring human activity patterns using taxicab static points. ISPRS International Journal of Geo-Information, 1(1), 89-107
Open this publication in new window or tab >>Exploring human activity patterns using taxicab static points
2012 (English)In: ISPRS International Journal of Geo-Information, ISSN 2220-9964, Vol. 1, no 1, p. 89-107Article in journal (Refereed) Published
Abstract [en]

This paper explores the patterns of human activities within a geographical space by adopting the taxicab static points which refer to the locations with zero speed along the tracking trajectory. We report the findings from both aggregated and individual aspects. Results from the aggregated level indicate the following: (1) Human activities exhibit an obvious regularity in time, for example, there is a burst of activity during weekend nights and a lull during the week. (2) They show a remarkable spatial drifting pattern, which strengthens our understanding of the activities in any given place. (3) Activities are heterogeneous in space irrespective of their drifting with time. These aggregated results not only help in city planning, but also facilitate traffic control and management. On the other hand, investigations on an individual level suggest that (4) activities witnessed by one taxicab will have different temporal regularity to another, and (5) each regularity implies a high level of prediction with low entropy by applying the Lempel-Ziv algorithm.

Keywords
Entropy, Human activities, Regularity, Scaling, Static points (SPs)
National Category
Computer and Information Sciences
Identifiers
urn:nbn:se:hig:diva-12970 (URN)10.3390/ijgi1010089 (DOI)000209465300006 ()2-s2.0-84886248057 (Scopus ID)
Projects
Hägerstrand project, Resemönster project
Available from: 2012-09-19 Created: 2012-09-19 Last updated: 2018-03-13Bibliographically approved
Jiang, B. & Jia, T. (2011). Agent-based simulation of human movement shaped by the underlying street structure. International Journal of Geographical Information Science, 25(1), 51-64
Open this publication in new window or tab >>Agent-based simulation of human movement shaped by the underlying street structure
2011 (English)In: International Journal of Geographical Information Science, ISSN 1365-8816, E-ISSN 1365-8824, Vol. 25, no 1, p. 51-64Article in journal (Refereed) Published
Abstract [en]

Relying on random and purposive moving agents, we simulated human movement in large street networks. We found that aggregate flow, assigned to individual streets, is mainly shaped by the underlying street structure, and that human moving behavior (either random or purposive) has little effect on the aggregate flow. This finding implies that given a street network, the movement patterns generated by purposive walkers (mostly human beings) and by random walkers are the same. Based on the simulation and correlation analysis, we further found that the closeness centrality is not a good indicator for human movement, in contrast to a long-standing view held by space syntax researchers. Instead we suggest that Google's PageRank and its modified version (weighted PageRank), betweenness and degree centralities are all better indicators for predicting aggregate flow.

Place, publisher, year, edition, pages
London: Taylor & Francis, 2011
Keywords
random walks, human movement, street networks, topological analysis, collective behavior, space syntax
National Category
Other Earth and Related Environmental Sciences Human Geography Information Systems
Identifiers
urn:nbn:se:hig:diva-10008 (URN)10.1080/13658811003712864 (DOI)000287572700004 ()
Available from: 2011-09-02 Created: 2011-09-02 Last updated: 2018-03-13Bibliographically approved
Jiang, B. & Jia, T. (2011). Zipf's law for all the natural cities in the United States: a geospatial perspective. International Journal of Geographical Information Science, 25(8), 1269-1281
Open this publication in new window or tab >>Zipf's law for all the natural cities in the United States: a geospatial perspective
2011 (English)In: International Journal of Geographical Information Science, ISSN 1365-8816, E-ISSN 1365-8824, Vol. 25, no 8, p. 1269-1281Article in journal (Refereed) Published
Abstract [en]

This article provides a new geospatial perspective on whether or not Zipf's law holds for all cities or for the largest cities in the United States using a massive dataset and its computing. A major problem around this issue is how to define cities or city boundaries. Most of the investigations of Zipf's law rely on the demarcations of cities imposed by census data, for example, metropolitan areas and census-designated places. These demarcations or definitions (of cities) are criticized for being subjective or even arbitrary. Alternative solutions to defining cities are suggested, but they still rely on census data for their definitions. In this article we demarcate urban agglomerations by clustering street nodes (including intersections and ends), forming what we call natural cities. Based on the demarcation, we found that Zipf's law holds remarkably well for all the natural cities (over 2–4 million in total) across the United States. There is little sensitivity for the holding with respect to the clustering resolution used for demarcating the natural cities. This is a big contrast to urban areas, as defined in the census data, which do not hold stable for Zipf's law.

Place, publisher, year, edition, pages
London: , 2011
National Category
Computer and Information Sciences
Identifiers
urn:nbn:se:hig:diva-10313 (URN)10.1080/13658816.2010.510801 (DOI)000295469300004 ()2-s2.0-80052956317 (Scopus ID)
Available from: 2011-09-22 Created: 2011-09-22 Last updated: 2018-03-13Bibliographically approved
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