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  • 1.
    Eshagh, Mehdi
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Avdelningen för Matematik, Data- och Lantmäteriteknik.
    Optimal Configuration for Monitoring Stations in a Wireless Localisation Network Based on Received Signal Strength Differences.2023Ingår i: Sensors, E-ISSN 1424-8220, Vol. 23, nr 3, artikel-id 1150Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    A smart city is a city equipped with many sensors communicating with each other for different purposes. Cybersecurity and signal security are important in such cities, especially for airports and harbours. Any signal interference or attack on the navigation of autonomous vehicles and aircraft may lead to catastrophes and risks in people's lives. Therefore, it is of tremendous importance to develop wireless security networks for the localisation of any radio frequency interferer in smart cities. Time of arrival, angle of arrival, time-difference of arrivals, received signal strength and received signal strength difference (RSSD) are known observables used for the localisation of a signal interferer. Localisation means to estimate the coordinates of an interferer from some established monitoring stations and sensors receiving such measurements from an interferer. The main goal of this study is to optimise the geometric configuration of the monitoring stations using a desired dilution of precision and/or variance-covariance matrix (VCM) for the transmitter's location based on the RSSD. The required mathematical models are developed and applied to the Arlanda international airport of Sweden. Our numerical tests show that the same configuration is achieved based on dilution of precision and VCM criteria when the resolution of design is lower than 20 m in the presence of the same constraints. The choice of the pathloss exponent in the mathematical models of the RSSDs is not important for such low resolutions. Finally, optimisation based on the VCM is recommended because of its larger redundancy and flexibility in selecting different desired variances and covariances for the coordinates of the transmitter.

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  • 2.
    Mårtensson, Stig-Göran
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Avdelningen för Matematik, Data- och Lantmäteriteknik. Faculty of Engineering and Sustainable Development, University of Gävle, Gävle (SWE).
    Simple computation of coordinates and uncertainty of ‘hidden’ points from two coordinated points that are collinear with the hidden point2022Ingår i: Survey review - Directorate of Overseas Surveys, ISSN 0039-6265, E-ISSN 1752-2706, Vol. 54, nr 387, s. 543-553Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Estimating the measurement uncertainties of coordinates of points that are not accessible by direct geodetic surveying (hidden points) is the topic of this study. The simplicity by which the uncertainties can be found for such hidden points when practicing indirect observations by total station or by Global Navigation Satellite System (GNSS) is demonstrated. A three-dimensional solution is obtained by total station observations using a two-prism hidden-point rod and a two-dimensional solution by GNSS observations on the ground. An intention with the study is that methods and results should apply for general geodetic purposes, like engineering surveying. The derived uncertainty formulae have been verified by Monte Carlo simulations. An important finding is their geometric dependence by the quotient between the two distances involved when two coordinated points are collinear with a third hidden point.

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  • 3.
    Sjöberg, Lars
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Avdelningen för Matematik, Data- och Lantmäteriteknik.
    Geoid model validation and topographic bias2022Ingår i: Journal of Geodetic Science, ISSN 2081-9919, E-ISSN 2081-9943, Vol. 12, nr 1, s. 38-41Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Recently a number of geoid campaigns were performed to verify different types of geoid and quasigeoid modeling techniques. Typically, GNSS-leveling was employed as an independent method, but in some cases zenith camera astronomic deflection data were also used in astrogeodetic determinations of the geoid and/or quasigeoid. However, due to the uncertainty in the topographic density distribution data (and thereby in orthometric heights), we conclude that neither GNSS-leveling nor astrogeodetic techniques can reliably verify differences between gravimetric geoid models at several centimeter levels in rough mountainous regions. This is because much the same topographic data are used both in the gravimetric geoid models and in their verifications by geometric and/or astrogeodetic geoid models. On the contrary, this is not a problem in verifying gravimetric quasigeoid models, as they are independent of the topographic density distribution, and so is the related normal height used in GNSS-leveling.

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  • 4.
    Sundararajan, Narasimman
    et al.
    Sultan Qaboos University, Department of Earth Sciences, Muscat, Oman.
    Eshagh, MehdiHögskolan Väst, Institutionen för ingenjörsvetenskap, Avdelningen för Matematik, Data- och Lantmäteriteknik.Saibi, HakimUnited Arab Emirates University,Abu Dhabi, United Arab Emirates.Meghraoui, MustaphaUniversité de Strasbourg, Strasbourg, France.Al-Garni, MansourKing Abdulaziz University, Jeddah, Saudi Arabia.Giroux, BernardCentre Eau Terre Environnement,Institut National de la Recherche Scientifique, Québec, Canada.
    On Significant Applications of Geophysical Methods: Proceedings of the 1st Springer Conference of the Arabian Journal of Geosciences (CAJG-1), Tunisia 20182019Samlingsverk (redaktörskap) (Övrigt vetenskapligt)
    Abstract [en]

    This edited volume is based on the best papers accepted for presentation during the 1st Springer Conference of the Arabian Journal of Geosciences (CAJG-1), Tunisia 2018. This special volume is of interest to all researchers practicing geosphysicists/seismologists, students of PG and UG in the fields of multifaceted Geoscience. Major applications with relevant illustrations presented in the volume are from Middle East. And therefore, this book no doubt would serve as a reference guide to all geoscientists and students in the broad field of Earth Science. This volume covers significant applications of gravity and magnetic methods, electrical and electromagnetic methods, refraction and reflection seismic methods besides a large number of study on earthquakes, tectonics and geological settings etc. The salient features of this volume are the interpretation and modeling of geophysical data of different nature

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