Towards forecasting and mitigating ionospheric scintillation effects on GNSS

The effect of the ionosphere on the signals of Global Navigation Satellite Systems (GNSS), such as the Global Positionig System (GPS) and the proposed European Galileo, is dependent on the ionospheric electron density, given by its Total Electron Content (TEC). Ionospheric time-varying density irregularities may cause scintillations, which are fluctuations in phase and amplitude of the signals. Scintillations occur more often at equatorial and high latitudes. They can degrade navigation and positioning accuracy and may cause loss of signal tracking, disrupting safety-critical applications, such as marine navigation and civil aviation. This paper addresses the results of initial research carried out on two fronts that are relevant to GNSS users if they are to counter ionospheric scintillations, i.e. forecasting and mitigating their effects. On the forecasting front, the dynamics of scintillation occurrence were analysed during the severe ionospheric storm that took place on the evening of 30 October 2003, using data from a network of GPS Ionospheric Scintillation and TEC Monitor (GISTM) receivers set up in Northern Europe. Previous results [1] indicated that GPS scintillations in that region can originate from ionospheric plasma structures from the American sector. In this paper we describe experiments that enabled confirmation of those findings. On the mitigation front we used the variance of the output error of the GPS receiver DLL (Delay Locked Loop) to modify the least squares stochastic model applied by an ordinary receiver to compute position. This error was modelled according to [2], as a function of the S4 amplitude scintillation index measured by the GISTM receivers. An improvement of up to 21% in relative positioning accuracy was achieved with this technnique.

Development, institutional and policy aspects of international migration between Africa, Europe and Latin America and the Caribbean

Incluye bibliografía

Galileo's surveying potential E5 pseudorange precision

New Galileo signals have great potential for pseudorange-based surveying and mapping in both optimal open-sky conditions and suboptimal under-canopy environments. This article reviews the main features of Galileo's E5 AItBO( and El (BOC signals, describes generation of realistic E5 and El pseudoranges with and without multipath sources, and presents anticipated horizontal positioning accuracy results, ranging from 4 centimeters (open-sky) to 14 centimeters (under-canopy) for E5/El.

Institutional, functional and financial aspects of the future of the Latin American and Caribbean Institute for Economic and Social Planning (ILPES) = Aspects institutionnels, fonctionnels et financiers liés à l'avenir de l'Institut Latino-Américain et des Caraïbes de Planification Economique et Sociale (ILPES)

Includes bibliography

Influência da combinação e modernização dos sistemas que integram o GNSS no georreferenciamento de imóveis rurais

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Development and optimization of graphic user interfaces (GUIs) for infrared spectrometers at the Telescopio Nazionale Galileo

This Phd thesis was entirely developed at the Telescopio Nazionale Galileo (TNG, Roque de los Muchachos, La Palma Canary Islands) with the aim of designing, developing and implementing a new Graphical User Interface (GUI) for the Near Infrared Camera Spectrometer (NICS) installed on the Nasmyth A of the telescope. The idea of a new GUI for NICS has risen for optimizing the astronomers work through a set of powerful tools not present in the existing GUI, such as the possibility to move automatically, an object on the slit or do a very preliminary images analysis and spectra extraction. The new GUI also provides a wide and versatile image display, an automatic procedure to find out the astronomical objects and a facility for the automatic image crosstalk correction. In order to test the overall correct functioning of the new GUI for NICS, and providing some information on the atmospheric extinction at the TNG site, two telluric standard stars have been spectroscopically observed within some engineering time, namely Hip031303 and Hip031567. The used NICS set-up is as follows: Large Field (0.25'' /pixel) mode, 0.5'' slit and spectral dispersion through the AMICI prism (R~100), and the higher resolution (R~1000) JH and HK grisms.

Climate change in Switzerland: a review of physical, institutional, and political aspects

Climate change is clearly discernible in observed climate records in Switzerland. It impacts on natural systems, ecosystems, and economic sectors such as agriculture, tourism, and energy, and it affects Swiss livelihood in various ways. The observed and projected changes call for a response from the political system, which in Switzerland is characterized by federalism and direct democratic instruments. Swiss climate science embraces natural and social sciences and builds on institutionalized links between researchers, public, and private stakeholders. In this article, we review the physical, institutional, and political aspects of climate change in Switzerland. We show how the current state of Swiss climate science and policy developed over the past 20 years in the context of international developments and national responses. Specific to Switzerland is its topographic setting with mountain regions and lowlands on both sides of the Alpine ridge, which makes climate change clearly apparent and for some aspects (tourist sector, hydropower, and extreme events) highly relevant and better perceivable (e.g., retreating glaciers). Not surprisingly the Alpine region is of central interest in Swiss climate change studies.

Tintenfass und Teleskop. Galileo Galilei im Schnittpunkt wissenschaftlicher, literarischer und visueller Kulturen im 17. Jahrhundert

Die Figur Galileo Galilei ist für die europäische Wissenschaftsgeschichte, für die Kulturwissenschaften und für eine wissensgeschichtlich orientierte Literatur- und Kunstwissenschaft von großem Interesse. In diesem Band werden die Überschneidungen, Wechselwirkungen und Transferprozesse zwischen den wissenschaftlichen und kulturellen Dimensionen untersucht, die für Galileis Profilierung als frühneuzeitlicher Wissenschaftler ebenso wichtig sind wie für die im weiteren Sinn kulturelle Wahrnehmung seiner Entdeckungen und seiner Schriften – vor allem in Literatur und Kunst. Der Band ist interdisziplinär konzipiert, um die fachlichen Einzelperspektiven von Literatur-, Kunst- und Kulturwissenschaftlern sowie Wissenschaftshistorikern zusammenzuführen. Analysiert werden Formen und Funktionen der Produktion, Konzeptualisierung und Repräsentation von Wissen sowie Aspekte der Diskussion und Diffusion von Galileis Wissensansprüchen im Kontext der Frühen Neuzeit. Mit dieser Fokussierung auf die im Schnittbereich verschiedener kultureller Formationen angesiedelte Etablierung Galileis liefert der Band somit einen Beitrag zur interdisziplinären Erforschung von Galileis Rolle und Rezeption in der europäischen Kultur- und Wissensgeschichte des 17. Jahrhunderts. Sprachen: Deutsch, Englisch, Italienisch