A stigmergy-based analysis of city hotspots to discover trends and anomalies in urban transportation usage

A key aspect of a sustainable urban transportation system is the effectiveness of transportation policies. To be effective, a policy has to consider a broad range of elements, such as pollution emission, traffic flow, and human mobility. Due to the complexity and variability of these elements in the urban area, to produce effective policies remains a very challenging task. With the introduction of the smart city paradigm, a widely available amount of data can be generated in the urban spaces. Such data can be a fundamental source of knowledge to improve policies because they can reflect the sustainability issues underlying the city. In this context, we propose an approach to exploit urban positioning data based on stigmergy, a bio-inspired mechanism providing scalar and temporal aggregation of samples. By employing stigmergy, samples in proximity with each other are aggregated into a functional structure called trail. The trail summarizes relevant dynamics in data and allows matching them, providing a measure of their similarity. Moreover, this mechanism can be specialized to unfold specific dynamics. Specifically, we identify high-density urban areas (i.e hotspots), analyze their activity over time, and unfold anomalies. Moreover, by matching activity patterns, a continuous measure of the dissimilarity with respect to the typical activity pattern is provided. This measure can be used by policy makers to evaluate the effect of policies and change them dynamically. As a case study, we analyze taxi trip data gathered in Manhattan from 2013 to 2015.Comment: Preprin

Stigmergy-based modeling to discover urban activity patterns from positioning data

Positioning data offer a remarkable source of information to analyze crowds urban dynamics. However, discovering urban activity patterns from the emergent behavior of crowds involves complex system modeling. An alternative approach is to adopt computational techniques belonging to the emergent paradigm, which enables self-organization of data and allows adaptive analysis. Specifically, our approach is based on stigmergy. By using stigmergy each sample position is associated with a digital pheromone deposit, which progressively evaporates and aggregates with other deposits according to their spatiotemporal proximity. Based on this principle, we exploit positioning data to identify high density areas (hotspots) and characterize their activity over time. This characterization allows the comparison of dynamics occurring in different days, providing a similarity measure exploitable by clustering techniques. Thus, we cluster days according to their activity behavior, discovering unexpected urban activity patterns. As a case study, we analyze taxi traces in New York City during 2015

Industrial sprawl and residential housing. Exploring the interplay between local development and land-use change in the Valencian Community, Spain

Urbanization in Mediterranean Europe has occurred in recent decades with expansion of residential, commercial and industrial settlements into rural landscapes outside the traditional metropolitan boundaries. Industrial expansion in peri-urban contexts was particularly intense in Southern Europe. Based on these premises, this work investigates residential and industrial settlement dynamics in the Valencian Community, Spain, between 2005 and 2015, with the aim to clarify the role of industrial expansion in total urban growth in a paradigmatic Mediterranean region. Since the early 1990s, the Valencian industrial sector developed in correspondence with already established industrial nodes, altering the surrounding rural landscape. Six variables (urban hierarchy, discontinuous settlements, pristine land under urban expansion, isolated industrial settlements, within- and out-of-plan industrial areas) were considered with the aim at exploring land-use change. Empirical results indicate a role of industrial development in pushing urban sprawl in coastal Valencia. A reflection on the distinctive evolution of residential and industrial settlements is essential for designing new planning measures for sustainable land management and containment of urban sprawl in Southern Europe. A comparative analysis of different alternatives of urban development based on quantitative assessment of land-use change provides guidelines for local development and ecological sustainability

Sopravvivenza e mortalità per causa

Analisi della mortalità generale e per causa nelle regioni italian

Towards local forms of sprawl: A brief reflection on mediterranean urbanization

Urban sprawl is a complex phenomenon that requires a comprehensive reflection on the most significant patterns and underlying processes. While the "sprawl" notion parallels hegemonic concepts such as economic competitiveness, social cohesion, and polycentric development, an integrated analysis of sprawl patterns and processes in paradigmatic socioeconomic contexts is increasingly required to reconcile dierent disciplinary visions, contributing to a holistic interpretation of metropolitan change. At the same time, sprawl is an increasingly evident product of local socioeconomic contexts all over the world. A comprehensive investigation of multifaceted, form-function relationships underlying sprawl-based on a quali-quantitative analysis of representative cases-is a crucial pre-requisite of both monitoring and policy actions at multiple spatial scales, from urban/regional to national/continental levels. The present contribution proposes a contextualization of the sprawl notion in Southern Europe-a socioeconomic context characterized by compact and continuous urbanization for a long time. An integrated approach based on a visual analysis of urban and peri-urban landscapes-integrated with an extended literature survey-allows for a definition of a specific sprawl model in Southern Europe, sharing some features with the United States ideal type of sprawl and showing peculiarities with respect to common models of urban dispersion typical of Northern and Western Europe. Policies aimed at containing urban dispersion may definitely benefit from a local-based definition of sprawl, considering the specificity of form-function relationships and the underlying socioeconomic context

Urbanisation-driven land degradation and socioeconomic challenges in peri-urban areas: Insights from Southern Europe

Climate change and landscape transformation have led to rapid expansion of peri-urban areas globally, representing new ‘laboratories’ for the study of human–nature relationships aiming at land degradation management. This paper contributes to the debate on human-driven land degradation processes by highlighting how natural and socioeconomic forces trigger soil depletion and environmental degradation in peri-urban areas. The aim was to classify and synthesise the interactions of urbanisation-driven factors with direct or indirect, on-site or off-site, and short-term or century-scale impacts on land degradation, focussing on Southern Europe as a paradigmatic case to address this issue. Assuming complex and multifaceted interactions among influencing factors, a relevant contribution to land degradation was shown to derive from socioeconomic drivers, the most important of which were population growth and urban sprawl. Viewing peri-urban areas as socio-environmental systems adapting to intense socioeconomic transformations, these factors were identified as forming complex environmental ‘syndromes’ driven by urbanisation. Based on this classification, we suggested three key measures to support future land management in Southern European peri-urban areas

Toward a ‘Migrant Trap’? Local Development, Urban Sustainability, Sociodemographic Inequalities, and the Economic Decline in a Mediterranean Metropolis

After years following the breakdown of the Great Recession in Europe, crisis-driven urban shrinkage can be adequately investigated considering changes over time in selected demographic indicators, with a specific focus on migration. Using official statistics and a literature review, the present study documents the inherent demographic decline in metropolitan Athens (Greece) as a response to economic stagnation after a long-lasting expansion. The empirical results of our study delineate metropolitan shrinkage in Southern Europe as a process associated with complex socioeconomic conditions leading to (possibly counterintuitive) demographic outcomes as far as migration trends are concerned. Recession has determined unsustainable economic conditions especially for non-native population segments, promoting both class and ethnic segregation. The negative migration balance in the 2010s led to an intense population decline hitting settlements made already demographically fragile because of low fertility and aging. Athens became a sort of ‘migrant trap’, being progressively unattractive for incoming migration flows—both internal and international—and losing an increasingly high number of non-native residents settling in the area, especially during the ‘gold’ decade of the 2004 Olympics. A sudden reduction in immigration rates reflected both economic (recession) and non-economic (population aging, fertility reduction, and childbearing postponement) factors, causing an incipient shrinkage after secular urban growth. The empirical results of our study add to the traditional literature on ‘industrial cities shrinkage’ in Europe and contribute to (re)formulate short- and medium-term development scenarios in large agglomerations, shedding further light on the role of migration in crisis-driven processes of urban decline in Mediterranean Europe

Population dynamics and agglomeration factors: A non-linear threshold estimation of density effects

Abstract: Although Southern Europe is relatively homogeneous in terms of settlement characteristics and urban dynamics, spatial heterogeneity in its population distribution is still high, and differences across regions outline specific demographic patterns that require in-depth investigation. In such contexts, density-dependent mechanisms of population growth are a key factor regulating socio-demographic dynamics at various spatial levels. Results of a spatio-temporal analysis of the distribution of the resident population in Greece contributes to identifying latent (density-dependent) processes of metropolitan growth over a sufficiently long time interval (1961-2011). Identification of density-dependent patterns of population growth contributes to the analysis of socioeconomic factors underlying demographic divides, possibly distinguishing between the effects of population concentration and dispersion. Population growth rates were non-linearly correlated with population density, highlighting a positive (or negative) impact of urban concentration on demographic growth when population is lower (or higher) than a fixed threshold (2800 and 1300 inhabitants/km2 in 1961 and 2011, respectively). In a context of low population density (less than 20 inhabitants/km2), the relationship between density and growth was again negative, contrasting with the positive and linear relationship observed in denser contexts. This result evidences a sort of 'depopulation' trap that leads to accelerated population decline under a defined density threshold. An improved understanding of density-dependent mechanisms of population growth and decline contributes to rethinking strategies of sustainable development and social policies more adapted to heterogeneous regional contexts

Rapidity of change in population age structures: A local approach based on multiway factor analysis

In the light of complex adaptive system thinking, population age structures in Europe have increasingly reflected the interplay between 'fast' and 'slow' socioeconomic dynamics driven by natural population growth and migration. Assuming the importance of demographic dynamics shaping regional growth in recent times, a diachronic analysis of local-scale population age structures was developed for 156 districts of Greece between 1971 and 2011. By using appropriate indicators, the analysis was aimed at demonstrating how 'fast' and 'slow' transitions contribute to socioeconomic change in both urban and rural areas. Acomprehensive analysis of change in population age structures between 1971 and 2011 allows identification of latent spatial structures as a result of population re-distribution from urban cores to broader rural regions. Following residential mobility, the empirical results of this study indicate (i) a late phase of urbanization (1971-1981) with population densification and settlement compactness, (i) a rapid suburbanization (1981-1991) consolidating distinctive demographic structures in urban and rural areas, (ii) a mild counter-urbanization (1991-2001) with moderate aging of suburban populations and (iii) a latent re-urbanization (2001-2011) reducing the suburban-urban divide in population age structures. Residential mobility contributed to a more balanced age structure during suburbanization and an increased demographic divide in the subsequent urban waves. A refined analysis of long-term population dynamics in metropolitan regions reflects spatial outcomes and latent aspects of demographic transitions shedding light on the debate over the future development of urban and rural societies in advanced economies