Abstract

Localization is a fundamental technology embedded — often unbeknownst to users — in many devices and services. First, this book reveals how localization systems are driving modern society. The core focus is then on the Global Positioning System (GPS), which is constantly rising in importance due to its global availability and low receiver cost. Still, high energy consumption and susceptibility to fake or reflected signals are challenges for GPS receivers. The limited endurance of battery-powered GPS receivers can be addressed by snapshot receivers which require as little as one millisecond of received satellite signals to determine their location. Using short signals reduces the active time and thus the energy consumption of a GPS receiver drastically. But short signals reduce the received signal energy, which impairs the localization robustness. The collective detection maximum likelihood method performs well with short signals. Furthermore, a tiny and low power snapshot GPS receiver hardware design allows location tracking for months or years using a coin cell. Spoofed GPS satellite signals pose a threat to an increasing number of critical systems relying on GPS. Determining multiple likely localization solutions instead of only one enables correct receiver localization despite malicious signals. Finally, an experimental localization system is presented that leverages status messages transmitted by aircraft. It aims at combining the ubiquitous availability and low receiver cost of GPS with the high signal strength of local localization systems like those based on WiFi or LTE signals. As such, it gives the prospect of robust and possibly indoor localization without the high setup costs of short- range localization systems. This book is suitable for readers with a technical background, but no prior knowledge of localization systems. Readers familiar with GPS can skip the introductory chapters and directly dive into the advanced material.

Abstract

Abstract. A significant advantage of OpenStreetMap data is its up-to-dateness. However, for rural and city planning, it is also of importance to access historical data and to compare the changes between new and old versions of the same area. This paper first introduces into a differentiated classification of changes on OpenStreetMap data sets. Then a methodology for an automated database-supported analysis of changes is presented. Beyond the information already provided from the OpenStreetMap server, we present a more detailed analysis with derived information. Based on this approach it is possible to identify objects with attributive or geometric changes and to find out how they exactly differ from their previous versions. The analysis shows in which regions mappers were active during a certain time interval. Furthermore, a time based approach based on various parameters to determine the quality of the data is presented. It provides a guideline of data quality and works without any reference data. Therefore, an indication about the development of OpenStreetMap in terms of completeness and correctness of the data in different regions is given. Finally, a conclusion and an outlook on open research questions are presented.

Document type: Article

Abstract

Large offshore wind farms are usually clustered around transmission grids to minimize the expense of transmission and due to space military zones, pipelines and constrains due to other uses such as nature preserves. However, this close proximity can undermine power production in downwind wind farms due to wakes from upwind wind farms. Therefore, the wind energy industry has great interest in determining the spatial dimensions of offshore wind farm wakes to assess the economical potential of planned wind farms. In this work we use wake measurements conducted by a research aircraft to evaluate the performance of a wind farm parameterization (WFP) in a mesoscale model during stably-stratified atmospheric conditions, in which the wake is expected to be the strongest. The observations were conducted on the 10 September 2016 within the project WIPAFF (Wind PArk Far Field) at the North Sea. The observations allow evaluation of both the horizontal and the vertical dimensions of the wake. The model simulates the length and most of the time the spatial dimensions of the wake. Further, we show that the largest potential for improving the performance of theWFP is rooted in an improvement of the background flow. This is due to the fact that the mesoscale model has problems representing the atmospheric boundary layer in the transition between land to open sea.

Abstract

In this paper, we characterise tourists most likely to visit a coastal destination by high-speed rail (HSR). Our data came from a survey conducted among HSR passengers during 2014’s high season (July and August) at Spain’s Camp de Tarragona and Alicante Stations, each of which is near a mass tourism destination on the Mediterranean coast: the Costa Daurada and the Costa Blanca, respectively. We used responses to the survey, which presented binary discrete-choice situations, to construct a database necessary for a logistic regression model that allowed us to examine how passenger profile, trip characteristics, and stay conditions influenced the use of HSR services on visits to each coastal destination. Results highlighted significant differences in the profiles of tourists who arrived at each destination by HSR and, in turn, that no specific tourist profile is associated with HSR, even for two stations that serve sunny beach destinations. Among its implications, to analyse travellers that HSR can attract, it is vital to consider the specific characteristics of each destination and its current market. This research was funded by the Spanish Ministry of Science and Innovation (GLOBALTUR–CSO2011–23004/GEOG; MOVETUR-CS02014-51785-R) to AG. Document type: Article

Abstract

Masonry arch bridges are found in large numbers on the rail networks of Europe and other parts of the world. However, the mode of response of masonry arch structures subjected to railway loading is little understood. To address this, an experimental study involving large-scale physical models of backfilled masonry arch bridges subjected to railway loading conditions has recently been conducted. This has explored the influence of the rail track bed system on bridge behaviour and on load carrying capacity. Tests indicate that the track bed system fundamentally alters the mode of response of the bridge system, and significantly increases load carrying capacity. Using the same test facility, load tests have also been used to explore and characterise the behaviour and performance of damaged arch bridges, with the test results obtained suggesting that although there is likely to be a reduction in overall capacity, even a significantly damaged arch bridge can still perform adequately under loading. This has important implications for bridge owners and assessment engineers."br/"\\ud "br/"\\ud "strong"Keywords:"/strong" masonry arch bridges, physical modelling, cyclic loading, rail track system, backfill. Document type: Article