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See detailSpatial modelling of feedback effects between urban structure and traffic-induced air pollution - Insights from quantitative geography and urban economics
Schindler, Mirjam UL

Doctoral thesis (2016)

Urban air pollution is among the largest environmental health risk and its major source is traffic, which is also the main cause of spatial variation of pollution concerns within cities. Spatial responses ... [more ▼]

Urban air pollution is among the largest environmental health risk and its major source is traffic, which is also the main cause of spatial variation of pollution concerns within cities. Spatial responses by residents to such a risk factor have important consequences on urban structures and, in turn, on the spatial distribution of air pollution and population exposure. These spatial interactions and feedbacks need to be understood comprehensively in order to design spatial planning policies to mitigate local health effects. This dissertation focusses on how residents take their location decisions when they are concerned about health effects associated with traffic-induced air pollution and how these decisions shape future cities. Theoretical analytical and simulation models integrating urban economics and quantitative geography are developed to analyse and simulate the feedback effect between urban structure and population exposure to traffic-induced air pollution. Based on these, spatial impacts of policy, socio-economic and technological frameworks are analysed. Building upon an empirical exploratory analysis, a chain of theoretical models simulates in 2D how the preference of households for green amenities as indirect appraisal of local air quality and local neighbourhood design impact the environment, residents' health and well-being. In order to study the feedback effect of households' aversion to traffic-induced pollution exposure on urban structure, a 1D theoretical urban economics model is developed. Feedback effects on pollution and exposure distributions and intra-urban equity are analysed. Equilibrium, first- and second-best are compared and discussed as to their population distributions, spatial extents and environmental and health implications. Finally, a dynamic agent-based simulation model in 2D further integrates geographical elements into the urban economics framework. Thus, it enhances the spatial representation of the spatial interactions between the location of households and traffic-induced air pollution within cities. Simulations contrast neighbourhood and distance effects of the pollution externality and emphasise the role of local urban characteristics to mitigate population exposure and to consolidate health and environmental effects. The dissertation argues that the consideration of local health concerns due to traffic-induced air pollution in policy design challenges the concept of high urban densification both locally and with respect to distance and advises spatial differentiation. [less ▲]

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See detailSpatial Multiplexing in Optical Feeder Links for High Throughput Satellites
Gharanjik, Ahmad UL; Liolis, Konstantinos; Shankar, Bhavani UL et al

in Spatial Multiplexing in Optical Feeder Links for High Throughput Satellites (2014, December 02)

Optical feeder links are an attractive alternative to the RF feeder links in satellite communications (SatCom). In this paper, we present initial results from an optical feeder link study. We discuss the ... [more ▼]

Optical feeder links are an attractive alternative to the RF feeder links in satellite communications (SatCom). In this paper, we present initial results from an optical feeder link study. We discuss the architecture of a geostationary earth orbit (GEO) satellite system based on optical feeder links. To mitigate the effects of cloud coverage, which is the main availability-limiting factor, Optical Ground Station (OGS) diversity is employed. Moreover, a spatial multiplexing scheme is considered. Assuming an ON-OFF channel model, the number of required OGSs to ensure availability and throughput requirements is analyzed [less ▲]

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See detailSpatial PAPR Reduction in Symbol-level Precoding for the Multi-beam Satellite Downlink
Spano, Danilo UL; Alodeh, Maha UL; Chatzinotas, Symeon UL et al

in IEEE SPAWC 2017 (2017, July)

In this work, a novel symbol-level precoding scheme is proposed, for managing the multi-user interference in the forward downlink channel of a multi-beam satellite system. Besides exploiting the ... [more ▼]

In this work, a novel symbol-level precoding scheme is proposed, for managing the multi-user interference in the forward downlink channel of a multi-beam satellite system. Besides exploiting the constructive interference effect, the proposed scheme aims at improving the robustness of the transmitted signals to the non-linear distortions of practical satellite systems. This is done by reducing the imbalances between the instantaneous power transmitted by the multiple antennas, which are detrimental in non-linear systems. More specifically, this work proposes a symbol-level precoding scheme performing the minimization of the spatial peak-to-average power ratio, under Quality-of-Service constraints. An iterative algorithm is proposed to solve the related optimization problem. Numerical results are presented to assess the performance of the proposed scheme, which outperforms the state of the art symbol-level precoding techniques in terms of spatial peak-to-average power ratio across the transmitting antennas. [less ▲]

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See detailSpatial patterns of land-use and neighbourhood diversity: a multilevel analysis of residential land prices in Luxembourg
Glaesener, Marie-Line UL; Caruso, Geoffrey UL

Scientific Conference (2014, August 28)

There is increasing interest in understanding how the spatial organisation of land uses within a neighbourhood impact on the perceived quality of a residential place. Not only this diversity may lead to ... [more ▼]

There is increasing interest in understanding how the spatial organisation of land uses within a neighbourhood impact on the perceived quality of a residential place. Not only this diversity may lead to higher attractiveness but also is usually seen as a key aspect of sustainable urban growth (mixed use development). Geoghegan et al. (1997) assume that increasing land use diversity might affect property values in two ways: negatively as they introduce higher chances of negative visual and noise externalities, but in the meantime positively as diversity may implicitly mean the proximity to important local urban amenities. Our paper aims at revealing the role of land-use diversity in determining the price of residential land, hence the attractiveness of a location beyond the structural qualities of houses. We conduct a hedonic price analysis of all residential land transactions across the Grand Duchy of Luxembourg between 2007 and 2011. Land-use diversity is measured by the Shannon diversity index. In addition to these unconventional geographical measures, we rely also on a multilevel modelling approach, which is still quite rare in land and housing hedonic literature (notable exceptions are Orford (2000), and Chasco and Le Gallo (2012)). We believe the multi-level approach is needed here to account for the nested nature of the data and to relax the assumption of a unitary equilibrium land market. As an alternative to the single-level model, the multilevel model accounts for the hierarchical structure of the spatial units, by modelling the variability at each of the considered levels and allowing individual observations within a particular spatial unit to be more similar than a random sample (Jones, 1991). Orford (2000) in particular emphasises the capacity of multi-level models to deal with spatial segmentations of the market and spatial dependence effects. In our paper we first identify the variability of transaction price at the different levels compared to the overall mean. Second, we check for spatial variations in the valuation of land-use diversity and parcel size in the residential land market. Third we test for remaining spatial effects via a cross-regressive multilevel model, as suggested by Chasco and Le Gallo (2012). Our results confirm the usefulness of the multilevel model approach and a negative valuation of close land-use diversity, whereas it is considered a positive externality in walking distance. Further, random coefficients for the Shannon indices confirm spatial variations in the valuation of land-use diversity. Via the cross-regressive multilevel model we test for remaining spatial effects and conclude that our model cleared up the entire spatial dependence in the land price data, conversely to the case in Chasco and Le Gallo (2012) and thus rather supporting suggestions from Orford (2000). [less ▲]

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See detailSpatial peak power minimization for relaxed phase M-PSK MIMO directional modulation transmitter
Kalantari, Ashkan UL; Tsinos, Christos UL; Soltanalian, Mojtaba UL et al

in Spatial peak power minimization for relaxed phase M-PSK MIMO directional modulation transmitter (2017)

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See detailSpatial play effects in a tangible game with an f-formation of multiple players
Jungmann, Manuela UL; Cox, Richard; Fitzpatrick, Geraldine

in Proceedings of the Fifteenth Australasian User Interface Conference (2014, January), 150

Drawing on Kendon's F-formation framework of social interaction, we analysed the game-space activity of collocated players engaged in a tangible multiplayer game. Game input from groups of 3 players ... [more ▼]

Drawing on Kendon's F-formation framework of social interaction, we analysed the game-space activity of collocated players engaged in a tangible multiplayer game. Game input from groups of 3 players interacting competitively in a natural spatial arrangement via balance-boards requiring whole-body movements was logged and analysed quantitatively. The spatial analysis of a range of players' activities in game-space revealed synergistic effects combining perceptual-motor factors with game-strategy behaviour which were reflected in preferred game-board playing regions. The findings illustrate the importance for HCI designers of considering interactions between human spatial behaviour, physical space and virtual game-space as games become increasingly embodied and social. [less ▲]

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See detailSpatial Risk Measures and their Local Specification: The Locally Law-Invariant Case
Föllmer, Hans UL

in Statistics & Risk Modeling (2014), 31(1), 79101

We consider convex risk measures in a spatial setting, where the outcome of a financial position depends on the states at different nodes of a network. In analogy to the theory of Gibbs measures in ... [more ▼]

We consider convex risk measures in a spatial setting, where the outcome of a financial position depends on the states at different nodes of a network. In analogy to the theory of Gibbs measures in Statistical Mechanics, we discuss the local specification of a global risk measure in terms of conditional local risk measures for the single nodes of the network, given their environment. Under a condition of local law invariance, we show that a consistent local specification must be of entropic form. Even in that case, a global risk measure may not be uniquely determined by the local specification, and this can be seen as a source of “systemic risk”, in analogy to the appearance of phase transitions in the theory of Gibbs measures [less ▲]

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See detailSpatial Risk Measures: Local Specification and Boundary Risk
Föllmer, Hans UL; Klüppelberg, Claudia

in Crisan, D.; Hambly, B.; Zariphopoulou, T. (Eds.) Stochastic Analysis and Applications 2014 - In Honour of Terry Lyons (2014)

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See detailThe spatial road to mathematics - from the relation between spatial skills and early mathematics towards interventions
Cornu, Véronique UL

Doctoral thesis (2018)

Early mathematical abilities, developed prior the onset of formal instruction, have been identified as a strong predictor of later mathematical achievement and numeracy, which goes along, in turn, with a ... [more ▼]

Early mathematical abilities, developed prior the onset of formal instruction, have been identified as a strong predictor of later mathematical achievement and numeracy, which goes along, in turn, with a variety of different life outcomes. Hence, unravelling the cognitive abilities associated with successful mathematical development is an important effort in the field of numerical cognition and developmental psychology. Abilities that are identified as predictors of mathematical development are potentially vital key targets of early interventions. By fostering these key abilities, children’s mathematical development should be positively influenced. The present thesis pursues two major aims. The first aim is to identify key predictors of mathematical development. More precisely, the present thesis studies whether spatial skills fall within the category of key predictors in young children. Findings illustrate that different aspects of spatial skills emerge as strong predictors of mathematics (study I). Findings further highlight, that spatial skills hold a pivotal role for mathematical skills with a prominent verbal component (study II). The second aim is concerned with the elaboration and scientific investigation of the effects of early interventions. A distinguishing feature of the present thesis is, that it is set in the Luxembourgish school setting. The latter is characterized by its heterogeneous student population from diverse language backgrounds. According to current statistics, around two-third of the children who attend Luxembourgish fundamental school do not speak Luxembourgish as a first language at home. Hence, an important number of children are not fluent in the language of instruction in preschool. Therefore, a central concern was to develop and implement early interventions that face the challenges posed by a multilingual school setting. For this reason, the language-neutral early mathematics training tool “MaGrid” was developed. MaGrid sets out to overcome the language-barrier in early mathematics education. On the content side, it encompasses a vast amount of number-specific and spatial training tasks. In the context of the present thesis two intervention studies (study III and study IV), including this tool, were run and yielded promising results. Results of these studies further add to unravelling the relation between spatial skills and mathematics and answering the question, whether the (early) road to mathematics is spatial indeed. [less ▲]

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See detailSpatial segregation and urban structure
Picard, Pierre M UL

in Regional Science and Urban Economics (2020), 59(3), 480-507

In this paper, we develop a model of spatial segregation mediated by competitive land prices. Agents of two groups consume city land and benefit from social interactions. Because of cultural or ethnic ... [more ▼]

In this paper, we develop a model of spatial segregation mediated by competitive land prices. Agents of two groups consume city land and benefit from social interactions. Because of cultural or ethnic differences, intragroup interactions are more frequent than intergroup ones. When group sizes differ, population groups sort into distinct neighborhoods. We characterize two‐ and three‐district urban structures. For high population ratios or strong intergroup interactions, only a three‐district city exists. In other cases, multiplicity of equilibria arises. Both groups generally rank these equilibria differently. However, when group sizes are similar, all individuals agree on which spatial equilibrium is best. [less ▲]

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See detailSpatial segregation and urban structure
Picard, Pierre M UL; mossay, pascal

in Journal of Regional Science (2019), 59(3), 480-507

In this paper, we develop a model of spatial segregation mediated by competitive land prices. Agents of two groups consume city land and benefit from social interactions. Because of cultural or ethnic ... [more ▼]

In this paper, we develop a model of spatial segregation mediated by competitive land prices. Agents of two groups consume city land and benefit from social interactions. Because of cultural or ethnic differences, intra-group interactions are more frequent than inter-group ones. When group sizes differ, population groups sort into distinct neighborhoods. We characterize two- and three-district urban structures. For high population ratios or strong inter-group interactions, only a three-district city exists. In other cases, multiplicity of equilibria arises. Both groups generally rank these equilibria differently. However, when group sizes are similar, all individuals agree on which spatial equilibrium is best. [less ▲]

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See detailSpatial Segregation and Urban Structure
Picard, Pierre M. UL; Mossay, Pascal

E-print/Working paper (2013)

In this paper, we study social interactions between two populations of individuals living in a city. Agents consume land and benefit from intra- and inter-group social interactions. We show that in ... [more ▼]

In this paper, we study social interactions between two populations of individuals living in a city. Agents consume land and benefit from intra- and inter-group social interactions. We show that in equilibrium segregation arises: populations get separated in distinct spatial neighborhoods. Two- and three-district urban structures are characterized. For high population ratios or strong inter-group interactions, only a three-district city exists. In other cases, multiplicity of equilibria arises. Moreover, for sufficiently low population ratios or very weak inter-group interactions, all individuals agree on which spatial equilibrium is best. [less ▲]

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See detailSpatial segregation and urban structure
Picard, Pierre M. UL

Presentation (2013)

Detailed reference viewed: 88 (6 UL)
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See detailThe spatial selection of heterogeneous firms
Okubo, Toshihiro; Picard, Pierre M. UL; Thisse, Jacques-François

in Journal of International Economics (2010), 82(2), 230-237

Empirical research on strategic alliances has focused on the idea that alliance partners are selected on the basis of social capital considerations. In this paper we emphasize instead the role of ... [more ▼]

Empirical research on strategic alliances has focused on the idea that alliance partners are selected on the basis of social capital considerations. In this paper we emphasize instead the role of complementary knowledge stocks (broadly defined) in partner selection, arguing not only that knowledge complementarity should not be overlooked, but that it may be the true causal force behind alliance formation. To marshal evidence on this point, we design a simple model of partner selection in which firms ally for the purpose of learning and innovating, and in doing so create an industry network. We abstract completely from network-based structural and strategic motives for partner selection and focus instead on the idea that firms’ knowledge bases must “fit” in order for joint leaning and innovation to be possible, and thus for an alliance to be feasible. The striking result is that while containing no social capital considerations, this simple model replicates the firm conduct, network structure, and contingent effects of network position on performance observed and discussed in the empirical literature. [less ▲]

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See detailSpatial Signature Estimation for Uniform Linear Arrays with Unknown Receiver Gains and Phases
Asztély, David; Swindlehurst, Andrew Lee; Ottersten, Björn UL

in IEEE Transactions on Signal Processing (1999), 47(8), 21282138

Detailed reference viewed: 63 (0 UL)
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See detailThe spatial Solow model
Camacho, Camen; Zou, Benteng UL

in Economics Bulletin (2004)

In this paper, we solve a Solow model in continuous time and space. We prove the existence of a solution to the problem and its convergence to a stationary solution. The simulations of various scenario in ... [more ▼]

In this paper, we solve a Solow model in continuous time and space. We prove the existence of a solution to the problem and its convergence to a stationary solution. The simulations of various scenario in the last section of the paper illustrates the convergence issue. [less ▲]

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See detailSpatial sorting, attitudes and the use of green space in Brussels
Schindler, Mirjam; Le Texier, Marion; Caruso, Geoffrey UL

in Urban Forestry and Urban Greening (2018), 31

Extensive evidence exists on the benefits provided by urban green space (UGS) but evidence is lacking about whether and how socio-economic benefits accrue to all residents or disproportionally depending ... [more ▼]

Extensive evidence exists on the benefits provided by urban green space (UGS) but evidence is lacking about whether and how socio-economic benefits accrue to all residents or disproportionally depending on their socio-economic status or residential location. We model joint effects of socio-economic and locational attributes on attitudes and use of UGS in Brussels (BE). The analysis is based on a survey conducted along an urban-suburban continuum with respondents sampled across non-park public space. Patterns of use are depicted by the frequency and the distance travelled to the most used UGS. Attitudes are analysed along three dimensions: willingness to (i) pay for UGS, (ii) trade-off housing for green space and (iii) substitute private for public green. Our results stress the importance of separating effects of attitudes from socio-economic and locational effects to quantify UGS use, and suggest endogenous effects of green space with residential sorting. [less ▲]

Detailed reference viewed: 249 (3 UL)