Location and accessibility are core concepts for land-value research. However, the perspective is still limited in their conceptual and methodological application to cities from the Global South. The objective of this research is to bridge concepts and definitions to comprehensively operationalize accessibility indicators and uncover its relation with residential land-values in Guatemala City. We developed a multivariate regression model using the following access metrics: (1) geographic-access indices that were computed using time-based analyses per transport mode; (2) geometric-access metrics estimated via Space Syntax at various spatial scales; (3) a proposed geometric via geographic-access metric computed as potential access to network centrality. A variable selection process allowed to assess the information contribution of each variable in building a parsimonious model. We assessed the model in the context of model variations that represent common approaches used in existing literature. Geographic access to the core business district has the highest impact on the land-values, followed by proximity to urban areas with high geometric-access, measured as geometric via geographic access. Geometric accessibility at neighbourhood and city-wide scales add spatialized information that contributes to a parsimonious model and reduces spatial dependence. The model yielded the highest goodness of fit and prediction accuracy compared with the model variations. We concluded that Guatemala City land-values follow a predominant monocentric structure. Additionally, potential access to vital urban areas as identified via Space Syntax denotes the presence of economic activities, or potential for such, which were not explicitly addressed through the geographic-access metrics. The results have limitations but pose methodological possibilities relevant for research and practice in similar Latin American cities.
Abstract. We consider the so-called spatially homogenous Kolmogorov-Vicsek model, a non-linear Fokker-Planck equation of self-driven stochastic particles with orientation interaction under the space-homogeneity. We prove the global existence and uniqueness of weak solutions to the equation. We also show that weak solutions exponentially converge to a steady state, which has the form of the Fisher-von Mises distribution.
a b s t r a c tThe Netherlands, like other European Union countries, is under intense pressure to increase its national share of energy from renewable sources in accordance with 2020 Kyoto Protocol obligations. Bioenergy in this context is especially interesting because it can replace liquid fuels so much in demand for transportation. In Europe, due to high population density, and intensive use of limited land resources, sources of biomass are quite limited. This study examines the potential of road verge for biomass production. In this case there is no conflict with agricultural production e "food for fuel" conflict e and very little problems with natural conservation, since we are focusing on already disturbed and heavily used and polluted areas. The road verge is also easily accessible and in most cases already has to be maintained and cultivated. We use GIS (Geographical information system) to identify the total area of land along the roads in the Netherlands that can potentially be used for bioenergy purposes. We then consider the opportunities and constraints of cultivating various types of biomass, mainly focusing on grasses and willow, short rotation coppice, as biomass sources on the road verge. Based on that, we distinguish between areas that are unavailable due to safety requirements, areas that are conditionally available provided that current regulations are revised and areas that are already unconditionally available. We assess the entire production chain in terms of Energy Return on Energy Invested (EROEI), and consider various combinations of grass and willow operations for bioenergy production. Looking at several roads in Eastern Overijssel, we have estimated that there is approximately 4.24e4.68 ha/km of road verge conditionally available along highways, A-roads, and some 0.80e2.67 ha/km available along local roads, N-roads. However, only 1.02e1.62 ha/km and 0.37e0.80 ha/km of A and N roads respectively are available unconditionally. The EROEI for some scenarios of both grass-based and willow-based production were quite high, 15e42, making such use of road verge quite promising.
Data scarcity is still a common barrier to adequately understanding urban access in Global South countries. Widely used location-based methods address the traditional definition of accessibility as the easiness to reach land-uses by means of available mobility modes. Space Syntax instead analyses accessibility as network centrality focusing only on the topological and geometric properties of urban layouts, making it comparatively less data-intense. However, the interpretation of its outputs is limited to its own theory. Knowledge is missing on how such metrics are comparable to the metrics produced by location-based methods. The objective of the research was to compare both approaches for mapping urban accessibility in two cities in Guatemala. Our hypothesis tested the assumption that Space Syntax metrics could consistently reflect accessibility conditions that so far have only been measured by location-based methods. We proposed an approach using volunteered geo-information and produced accessibility maps following both approaches that were then compared using Pearson correlations. Space Syntax metrics at low and high radii are consistently correlated with location-based access to land uses that reflect location quality at neighbourhood and city-wide scale correspondingly. Space Syntax metrics at lower radii reflect time-based access restrictions either posed in the location-based analyses or by reduced accessibility by public transport. The hypothesis acceptance, p < 0.01, expands the scope of accessibility knowledge derivable from limited data availability using Space Syntax, which is relevant for its applicability in data-scarce contexts by planners and researchers in the Global South. Rather than replacing location-based methods Space Syntax offers an important complementary measure to geographical accessibility. This having been said, Space Syntax could contribute to early-stage planning by gaining overall insights into patterns of urban access.
During the search for spatial data resources, users, both experts and non-experts in the geoinformation field, are expected to know what type of spatial data resource they need, and in which clearinghouse or geoportal to search. In the case of success, they are still left with the decision on fitness for use, based on complex metadata, for the few cases where such metadata exists. To aid the search for spatial data resources, we propose a system for guided search for spatial data resources called GUESS. This system enhances current search engines with decision intelligence on fitness for use. GUESS works with profiles that contain data about users and about spatial data resources. From a free-form search request, GUESS identifies the spatial extent and the application domain, and searches for spatial data resources that comply with quality requirements in that domain. As a result, GUESS recommends a spatial data resource that best fits the user's needs. We illustrate capabilities of the proposed system on a request by a fictional user of a spatial data resource that is frequently present in the geoinformation world.
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