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Beschreibung: Support system for safe driving heavily depends on global navigation satellite system. Pseudoranges between satellites and vehicles are measured to compute vehicles’ positions and their relative positions. In urban areas, however, multipath errors (MPEs) in pseudoranges, caused by obstruction and reflection of roadside buildings, greatly degrade the precision of relative positions. On the other hand, simply removing all reflected signals might lead to a shortage of satellites in fixing positions. In our previous work, we suggested solving this dilemma by cooperative relative positioning (CoRelPos) which exploits spatial correlation of MPEs. In this paper, we collected the trace data of pseudoranges by driving cars in urban areas, analyzed the properties of MPEs (specifically, their dependency on signal strength, elevation angles of satellites, and receivers’ speeds), and highlighted their spatial correlation. On this basis, the CoRelPos scheme is refined by considering the dynamics of MPEs. Evaluation results under practical vehicular scenarios confirm that properties of MPEs can be exploited to improve the precision of relative positions.

Print ISSN: 1687-5990

Digitale ISSN: 1687-6008

Thema: Architektur, Bauingenieurwesen, Vermessung , Geologie und Paläontologie

Publiziert von Hindawi

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Human Capital, Skills, and Uneven Intraurban Employment Growth: The Case of Göteborg, Sweden, 1990–2008 (2014)

Jonathan Borggren and Rikard H. Eriksson

Hindawi

In: Urban Studies Research

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Publikationsdatum: 2014-03-13

Beschreibung: Recent research has elucidated the role of talents to explain urban growth differences but it remains to be shown whether urban dynamics, such as human capital and a mixed local population, can be linked to intraurban employment growth. By use of a unique longitudinal database, we track the economic development through the lens of intraurban employment growth of a number of primary urban areas (PUA) in Göteborg, Sweden. Regarding factors influencing employment growth, we find that relative concentrations of human capital protect areas from rising unemployment during severe recession (1990–1993) and recovery (1990–2000) while the composition of skills is beneficial during recovery (1990–2000) and long-term growth (1990–2008). Our findings suggest that neither too high concentrations of creative occupations nor too low ones are beneficial. Thus, human capital drives much of the employment changes in relation to the recession and early transition from manufacturing to service but composition of skills is more relevant for explaining long-term intraurban employment growth.

Print ISSN: 2090-4185

Digitale ISSN: 2090-4193

Thema: Architektur, Bauingenieurwesen, Vermessung , Geographie

Publiziert von Hindawi

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Use of the Wavelet Transform for Interference Detection and Mitigation in Global Navigation Satellite Systems (2014)

Luciano Musumeci and Fabio Dovis

Hindawi

In: International Journal of Navigation and Observation

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Publikationsdatum: 2014-02-27

Beschreibung: Radio frequency interference detection and mitigation are becoming of paramount importance due to the increasing number of services and applications based on the position obtained by means of Global Navigation Satellite Systems. A way to cope with such threats is the implementation in the receiver of advanced signal processing algorithm able to raise proper warning or improve the receiver performance. In this paper, we propose a method based on the Wavelet Transform able to split the useful signal from the interfering component in a transformed domain. The wavelet packet decomposition and proper statistical thresholds allow the algorithm to show very good performance in case of multiple pulse interference as well as in the case of narrowband interference, two scenarios in which traditional countermeasures might not be effective.

Print ISSN: 1687-5990

Digitale ISSN: 1687-6008

Thema: Architektur, Bauingenieurwesen, Vermessung , Geologie und Paläontologie

Publiziert von Hindawi

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Neighborhood Social Capital, Neighborhood Disadvantage, and Change of Neighborhood as Predictors of School Readiness (2014)

Charles Jones and Jing Shen

Hindawi

In: Urban Studies Research

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Publikationsdatum: 2014-02-27

Beschreibung: Neighborhood income and social capital are considered important for child development, but social capital has rarely been measured directly at an aggregate level. We used Canadian data to derive measures of social capital from aggregated parental judgments of neighborhood collective efficacy and neighborhood safety. Measures of neighborhood income came from Census data. Direct measures of preschoolers’ school readiness were predicted from neighborhood-level variables, with regional indicators and household/parental characteristics taken into account. Our findings show that (1) residing in Quebec, being Black, and having a parent who was born outside Canada are positively associated with children’s living in disadvantaged or low collective efficacy neighborhoods as well as with their living in low-income households. (2) Children’s odds of residential mobility were reduced when the origin neighborhood had higher collective efficacy but increased when the family rented rather than owned. (3) Both neighborhood collective efficacy and children’s ever having lived in a poor neighborhood were correlated with receptive vocabulary scores, but results were mixed for other cognitive dimensions. Children of younger mothers scored worse on receptive vocabulary. There were similar patterns for demographic predictors related to visible minority status, sibship size, and birth order. Neighborhood average income had no effect on cognitive outcomes when the region was controlled.

Print ISSN: 2090-4185

Digitale ISSN: 2090-4193

Thema: Architektur, Bauingenieurwesen, Vermessung , Geographie

Publiziert von Hindawi

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