Environment and Planning B: Urban Analytics and City Science

Peering between network providers is modeled as a set of interconnections at hub nodes. The paper employs probabilistic methods to determine the likelihood of a path between nodes, under a variety of simulated disruptions or failures of parts of a network. Reliability is measured as the probability of withstanding failure of network components such as nodes or linkages. A reliability envelope is devised in order to define a range of impacts—with the recognition that the damage to subsets of the network can vary from a relatively benign effect to a much more critical or lethal impact. Thus, we describe a range of scenarios from best to worst, within the same level of infrastructure loss. With the use of simulation data for the United States, results show the critical role of major hubs in sustaining communication among cities. In the paper we highlight especially reliable nodes (for example, Chicago and Atlanta) and those that are most susceptible (for example, Birmingham, Alabama, and Nashville, Tennessee). Failure in major hub cities such as Chicago, Dallas, and San Francisco would significantly influence adjacent areas and could cause severe degradation for the entire network with a loss of resiliency to below tolerable levels. An important finding is that various patterns in the reliability envelope can be influenced by factors such as network structures, hub structures, and geographical locations.

The basic rules of central place networks are abstracted and formulated as three geometric series scaling laws, which can be transformed into several power laws associated with fractal structure. The scaling laws might be the Rosetta Stone to understand the complexity of human geographical systems because they take the form of Horton and Strahler's laws in geomorphology and Gutenberg and Richter's laws in seismology indicative of fractals and self-organized criticality (SOC). An empirical analysis is conducted with the use of data from southern Germany, given by Christaller. The fractal dimensions, D_f, of four systems are calculated as follows: D_f is 1.733 for Munich, 1.685 for Nuremberg, 1.837 for Stuttgart, and 1.481 for Frankfurt. SOC theory is employed to interpret the fractality of central places, and the power laws are seen as signatures of feasible optimality, thus yielding further support to the suggestion that optimality of the system as a whole explains the dynamic origin of fractal forms in nature.

The compact-city paradigm has received increased attention worldwide for its ability to achieve sustainable development. However, the claim that the compact-city paradigm contributes to sustainability has not been sufficiently verified. In this study we evaluate how major concepts in the compact-city paradigm affect urban sustainability. Correspondingly, the complementary strategies for facilitating compact-city progress are recommended. Structural equation modeling was applied to ninety-two samples of medium-sized or small-sized cities in Taiwan. Latent variables and observed variables were analyzed in the model's structure. According to the results a high-density pattern and intensification negatively affect the environmental and social sustainability, but positively affect economic sustainability. Furthermore, mixture of land use is beneficial to economic sustainability, and does not significantly affect environmental or social sustainability. On the basis of the empirical results, strategies that guide the compact-city paradigm toward the goals of sustainability are also proposed.

The notion that industrial systems can be redesigned to reflect ‘lessons from nature’ has led to the emergence of a new discipline known as ‘industrial ecology’. In this paper I provide a brief overview of the principles that underpin the discipline, and provide a critical evaluation of the extent to which it is guided by ecology or simply uses the label for rhetorical support. I suggest that simply appealing to ecological analogies is not sufficient to ensure that the impacts of industrial activities are reduced. Further, I propose that the technical process of industrial design needs to be embedded in legitimate social processes if social acceptability is to be attained.

Community corrections centers (CCCs, or ‘halfway houses’) represent a community-based justice strategy intended to reintegrate offenders into civil society. Site selection for these facilities is complicated by negative perceptions of CCC impacts on the part of potential host communities. I solve the CCC-location problem through the use of a framework based on value-focused thinking and quantitative decision models. The first of two mathematical models for CCC location is a novel integer programming formulation that incorporates neighborhood characteristics and equity considerations; the second is a straightforward application of the analytic hierarchy process. These models are applied to a case study in the city of Pittsburgh, PA. In contrast to traditional dispersion models, the mathematical programming model identifies sites in high-amenity neighborhoods which are argued to be associated with beneficial CCC client outcomes. Also, I find that sites selected using multicriteria decision models are relatively easy to generate and are competitive with mathematical programming models in terms of objective function measures.

Geospatial information is a fundamental component of many crisis management activities. However, current geospatial technologies do not support work by crisis management personnel, most of whom are not technology specialists—a key impediment is that the technologies require the user to learn the system's language. In addition, geospatial technologies are not ‘collaboration friendly’—they impede rather than facilitate group work. In this paper we address both issues by presenting (1) a theoretical framework for understanding the roles of visual mediation in map-supported human–human dialogues, and (2) a computational approach for enabling such roles in collaborative spatial decisionmaking contexts. Building upon our initial implementation of a map-mediated collaborative environment, the DAVE_G system [a natural, multimodal, dialogue-enabled interface to geographical information systems (GIS)], we model human–GIS and human–GIS–human dialogues as complex visual-cognitive signification processes in which maps become dynamic facilitators. Using a scenario simulating two crisis managers dealing with a major nuclear release event, we demonstrate how visual display (in DAVE_G) actively mediates human–human dialogue directed to situation assessment and action planning in real applications.

Planning at the edge of cities has, in the past, largely been concerned with containment, with the promotion of more compact urban form, and with the planned separation of rural and urban land use and activities. However, there has been some inevitable blurring of these uses, to create a unique landscape—an interface between town and country—sometimes labelled the rural–urban fringe. This landscape has been created more by fortune than design: less favoured urban uses—sewage works, mental institutions, asylum centres, breakers' yards, etc—have been pushed away from residential areas. Rural uses, mainly farming and forestry, have become mingled with this particular assemblage of urban activities to create a hybrid landscape. Planning, however, has been a relatively inert force at the edge: seeking to contain (perhaps through greenbelts) but not seeking to improve or to manage. In England, our principal focus in this paper, a number of commentators have expressed a concern for this apparent inertia, arguing that planning could do more to ‘manage’ the fringe, creating new social, economic, and environmental opportunities. We draw on a review of policies and programmes affecting the fringe, and argue that spatial planning—able to integrate land uses, and different activities and interests-may create such opportunities. We highlight what planning might seek to achieve at the edge, and how any programme of change might be driven forward.