6,127 research outputs found

    Cosmic background explorer (COBE) navigation with TDRSS one-way return-link Doppler in the post-helium-venting phase

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    A navigation experiment was performed which establishes Ultra-Stable Oscillator (USO) frequency stabilized one way return link Doppler TDRSS tracking data as a feasible option for mission orbit determination support at the Goddard Space Center Flight Dynamics Facility. The study was conducted using both one way and two way Tracking and Data Relay Satellite System (TDRSS) tracking measurements for the Cosmic Background Explorer (COBE) spacecraft. Tracking data for a 4 week period immediately follow the depletion of the helium supply was used. The study showed that, for both definitive orbit solution and short term orbit prediction (up to 4 weeks), orbit determination results based on one way return link Doppler tracking measurements are comparable to orbit determination results based on two way range and two way Doppler tracking measurements

    Fifth Annual Flight Mechanics/Estimation Theory Symposium

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    Various aspects of astrodynamics are considered including orbit calculations and trajectory determination. Other topics dealing with remote sensing systems, satellite navigation, and attitude control are included

    De actor secundário a actor principal : o Supremo Tribunal e a "revolução constitucional" em Israel

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    Analisa o surgimento do Estado de Israel e de suas instituições, apontando os problemas do judiciário israelita. Em seguida, discorre sobre a "revolução constitucional" ocorrida no país na década de 90 e conclui que a criação do Estado laico constituiu um enorme desafio à natureza identitária da religião judaica

    Normalization procedure for relaxation studies in NMR quantum information processing

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    NMR quantum information processing studies rely on the reconstruction of the density matrix representing the so-called pseudo-pure states (PPS). An initially pure part of a PPS state undergoes unitary and non-unitary (relaxation) transformations during a computation process, causing a "loss of purity" until the equilibrium is reached. Besides, upon relaxation, the nuclear polarization varies in time, a fact which must be taken into account when comparing density matrices at different instants. Attempting to use time-fixed normalization procedures when relaxation is present, leads to various anomalies on matrices populations. On this paper we propose a method which takes into account the time-dependence of the normalization factor. From a generic form for the deviation density matrix an expression for the relaxing initial pure state is deduced. The method is exemplified with an experiment of relaxation of the concurrence of a pseudo-entangled state, which exhibits the phenomenon of sudden death, and the relaxation of the Wigner function of a pseudo-cat state.Comment: 9 pages, 5 figures, to appear in QI

    The unstructured Scaldis model: a new 3D high resolution model for hydrodynamics and sediment transport in the tidal Scheldt

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    In the framework of the projects "Integral Plan for the Upper Sea Scheldt" and "Agenda for the Future", the SCALDIS model, a new unstructured high resolution model of the tidal Scheldt is developed in TELEMAC 3D (Telemac-Mascaret software platform). Starting from the stated model purpose, a weighted dimensionless cost function is set up that attributes equal weight to the vertical and the horizontal tide. By adapting the bottom roughness, the cost function is minimized during model calibration. Quantification of the model skill and cost function calculation is done using the VIMM toolbox which is developed and maintained at Flanders Hydraulics Research. The quantified model skill of the SCALDIS model shows that the model is well suited to assess the effects of changing the bathymetry and geometry of the Scheldt river on water levels, velocities, tracer dispersion and residence times, and that the hydrodynamics can be used as the basis for sediment transport calculations (both cohesive and non-cohesive)

    Assessing the intensity of cooperation: a study of joint delegation of municipal functions to inter-municipal associations

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    Talking is cheap, at least in the short term; elected officials may profess their preferences for IMC and yet deny IMA organisations the necessary resources to fulfil their missions. Driven by a focus on revealed preferences for inter-municipal cooperation, the article aims to answer two questions: Why do some IMA exhibit a high level of commitment on the part of their local government members whereas others remain underutilised, reflecting a choice by local governments to retain these responsibilities themselves? How does this commitment to IMAs vary over time? We use data from 25 IMAs over a 10-year period (2008–2018) in Portugal to assess the intensity of cooperation among Portuguese local governments through stand-alone organisations. The panel analysis regression supports the hypotheses that a larger number of local governments involved in IMAs and higher levels of heterogeneity among them make cooperation more difficult. In contrast, longer interaction in IMAs reinforces the intensity of cooperation.This work was supported by the Research Centre for Political Science (UIDB/CPO/ 00758/2020), University of Minho/University of Évora, supported by the Portuguese Foundation for Science and Technology (FCT) and the Portuguese Ministry of Education and Science
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