An Objective Analysis Technique for Constructing Three-Dimensional Urban-Scale Wind Fields

An objective analysis procedure for generating mass-consistent, urban-scale three-dimensional wind fields is presented together with a comparison against existing techniques. The algorithm employs terrain following coordinates and variable vertical grid spacing. Initial estimates of the velocity field are developed by interpolating surface and upper level wind measurements. A local terrain adjustment technique, involving solution of the Poisson equation, is used to establish the horizontal components of the surface field. Vertical velocities are developed from successive solutions of the continuity equation followed by an iterative procedure which reduces anomalous divergence in the complete field. Major advantages of the procedure are that it is computationally efficient and allows boundary values to adjust in response to changes in the interior flow. The method has been successfully tested using field measurements and problems with known analytic solutions

Amplifying Quiet Voices: Challenges and Opportunities for Participatory Design at an Urban Scale

Many Smart City projects are beginning to consider the role of citizens. However, current methods for engaging urban populations in participatory design activities are somewhat limited. In this paper, we describe an approach taken to empower socially disadvantaged citizens, using a variety of both social and technological tools, in a smart city project. Through analysing the nature of citizens’ concerns and proposed solutions, we explore the benefits of our approach, arguing that engaging citizens can uncover hyper-local concerns that provide a foundation for finding solutions to address citizen concerns. By reflecting on our approach, we identify four key challenges to utilising participatory design at an urban scale; balancing scale with the personal, who has control of the process, who is participating and integrating citizen-led work with local authorities. By addressing these challenges, we will be able to truly engage citizens as collaborators in co-designing their city

Development of a Fast and Detailed Model of Urban-Scale Chemical and Physical Processing

Abstract and PDF report are also available on the MIT Joint Program on the Science and Policy of Global Change website (http://globalchange.mit.edu/).A reduced form metamodel has been produced to simulate the effects of physical, chemical, and meteorological processing of highly reactive trace species in hypothetical urban areas, which is capable of efficiently simulating the urban concentration, surface deposition, and net mass flux of these species. A polynomial chaos expansion and the probabilistic collocation method have been used for the metamodel, and its coefficients were fit so as to be applicable under a broad range of present-day and future conditions. The inputs upon which this metamodel have been formed are based on a combination of physical properties (average temperature, diurnal temperature range, date, and latitude), anthropogenic properties (patterns and amounts of emissions), and the surrounding environment (background concentrations of certain species). Probability Distribution Functions (PDFs) of the inputs were used to run a detailed parent chemical and physical model, the Comprehensive Air Quality Model with Extensions (CAMx), thousands of times. Outputs from these runs were used in turn to both determine the coefficients of and test the precision of the metamodel, as compared with the detailed parent model. The deviations between the metamodel and the parent mode for many important species (O3, CO, NOx, and BC) were found to have a weighted RMS error less than 10% in all cases, with many of the specific cases having a weighted RMS error less than 1%. Some of the other important species (VOCs, PAN, OC, and sulfate aerosol) usually have their weighted RMS error less than 10% as well, except for a small number of cases. These cases, in which the highly non-linear nature of the processing is too large for the third order metamodel to give an accurate fit, are explained in terms of the complexity and non-linearity of the physical, chemical, and meteorological processing. In addition, for those species in which good fits have not been obtained, the program has been designed in such a way that values which are not physically realistic are flagged. Sensitivity tests have been performed, to observe the response of the 16 metamodels (4 different meteorologies and 4 different urban types) to a broad set of potential inputs. These results were compared with observations of ozone, CO, formaldehyde, BC, and PM10 from a few well observed urban areas, and in most of the cases, the output distributions were found to be within ranges of the observations. Overall, a set of efficient and robust metamodels have been generated which are capable of simulating the effects of various physical, chemical, and meteorological processing, and capable of determining the urban concentrations, mole fractions, and fluxes of species, important to human health and the climate.Federal Agencies and industries that sponsor the MIT Joint Program on the Science and Policy of Global Change

WETWALL - an innovative design concept for the treatment of wastewater at an urban scale

Rising temperatures, increasing food demand and scarcity of water and land resources highlight the importance of promoting the sustainable expansion of agriculture to our urban environment, while preserving water resources. Treating urban wastewaters, such as greywater and hydroponic wastewater, may represent a strategic point for the implementation of urban farming, ensuring food security, reducing pressures on water resources and promoting climate change mitigation. The WETWALL design concept proposes a unique ecotechnology for secondary wastewater treatment at an urban scale, which brings the novelty of a modular living wall hybrid flow. This concept is based on the integration of two established nature-based solutions/ecomimetic designs: constructed wetlands and a modular living walls. First presented is an overview about the state of the art in the scope of living walls treating wastewater, in order to identify the main design aspects related to the performance of such systems, which mainly concerns the removal of nitrates and phosphates. Second, the WETWALL design concept is presented. A scheme regarding the selection of the main components, such as plants and substrate, is proposed, and potential structure developments and operation strategies are discussed. In addition, considering the scope of integrating the circular economy with the design process, potential interactions between this technology and the urban environment are discussed. The main goal of this article is to substantiate the potential of the WETWALL design concept as an innovative wastewater treatment at an urban scale.Biggest thanks to the National Council for Scientific and Technological Development – Brazil (CNPQ), for their financial support (doctoral fellowship). The authors also would like to thank the UNESCO Chair on Sustainability of the Polytechnic University of Catalonia (Spain), the Aarhus University (Denmark) and the research groups GREA (2014 SGR 123), DIOPMA (2014 SGR 1543) and GICITED (2014 SGR 1298)

Housing, the hyper-precarization of asylum seekers and the contested politics of welcome on Tyneside

This paper analyses the role of housing in shaping the contested politics of welcome in the North East of England. It argues that changes to state provision of asylum seeker housing and the introduction of new legislation to create a hostile internalised bordering regime have led to a hyper-precarization of asylum seekers, which has been contested through a range of political projects at the urban scale. On Tyneside, these projects coalesced around struggles for improvements to state-provided accommodation for asylum seekers. The analysis reveals that whilst asylum housing has become key to the articulation of the politics of welcome within cities outside of London, it is spatially and temporally differentiated. The differential political projects shaping ‘welcoming’ at the urban scale emerge from contestation between a range of actors. On Tyneside, this contested politics arises from two key shifts: a change in national and local government in 2010 and 2011, which catalysed an oppositional politics of welcome amongst regional politicians; and the emergence of a new civil society initiative on Tyneside, whose direct action destabilised the relatively sedimented existing political landscape of welcome in the region, making space for differentiated asylum seeker political subjectivities

On Amenities, Natural Advantage and Agglomeration

A prominent feature of economic geography in America is the positive correlation amongst local incomes, housing costs and city population. This paper embeds a “black box” agglomeration economy within a more neoclassical general equilibrium model of local wages, rents and population to assess the ability of various conceptual models to predict this cross-sectional variation. I use exogenous changes in housing supply to induce changes in population and examine whether the changes in rents and wages move in the same direction under neo-classical assumptions, agglomeration economies in production, congestion in production, or urbanization economies in consumption. On their own, none of these urban scale effects generate the observed pattern. All urban scale effects generate a negative correlation between rents and population. Combining natural advantage with the urban scale effects improves the models’ output. It generally predicts positive correlations amongst the three variables, although some of these effects are ambiguous in the production agglomeration model. If natural advantage and housing supply constraints vary more-or-less independently, the results suggest a better fit of the data is provided by either the congestion in production or the agglomeration in consumption models. The micro-economics of such consumption-oriented agglomeration economies have received less attention than production-oriented agglomeration economies. The results of this model thus suggest that consumption-oriented agglomeration and congestion should receive more attention in the future.agglomeration, urbanization economies, congestion, regional equilibrium, natural advantage, economic geography

BLUE-based NO2 data assimilation at urban scale

International audienceWe aim at optimally combining air quality computations, from the Gaussian model ADMS Urban, and ground observations at urban scale. An ADMS simulation generated NO2 concentration fields across Clermont-Ferrand (France) down to street level, every 3 h for the full year 2008. A monitoring network composed of nine fixed stations provided hourly observations to be assimilated. Every 3 h, we compute the so-called BLUE (best linear unbiased estimator), which is a concentration field merging ADMS outputs and ground observations. Its error variance is supposed to be minimal under given assumptions regarding the errors on observations and model simulations. A key step lies in the modeling of error covariances between the computed NO2 concentrations across the city. We introduce a parameterized covariance which heavily relies on the road network. The covariance between two locations depends on the distance of each location to the road network and on the distance between the locations along the road network. Efficient parameters for the covariances are primarily chosen according to prior assumptions, χ2 diagnosis and leave-one-out cross-validations. According to the cross-validations, the improvements due to the assimilation seem moderately far from the observation network, but the root mean square error roughly decreases by 30-50% in the main city where the station density is high. The method is computationally tractable for the generation of improved concentration fields over a long period, or for day-to-day forecasts

Systematisation of seismic mitigation planning at urban scale

This chapter explores the relation between the seismic mitigation planning that was developed to contribute to minimise effects at urban scale, which arise within the seismic impact. In this sense, it deepens the notion that interdependence, solidarity and cohesion of the different morphological constituents promote a better prepared built fabric, when facing catastrophic phenomena of seismic origin. Preventive approaches and reactive measures arising from the testimony of earthquake-resistant culture in Portugal are also mentioned. From the recognition of the importance of local know-how, infers a set of logical that evidence conditions to transcend the respective vernacular context, making it possible to generically systematize them.Portuguese Science and Technology Foundation (FCT) to the research project ‘SEISMIC-V – Vernacular Seismic Culture in Portugal’ (PTDC/ATPAQI/ 3934/2012