88,710 research outputs found
Some aspects of the intellectual relations between Galileo and the Jesuits
No full textDuring the years from 1616 (when the Decree prohibiting
two Copernican propositions was issued by the Congregation of the Index) to 1623 (when Galileo published The Assayer) Jesuits of the Roman College made several attempts to draw Galileo into further discussion of his work. This was not with the intention of checking his obedience to the Decree, but in order to test the strength of any continuing work. The evidence suggests that there were certain Jesuits, who were willing, even determined, to re-open debate with him. They made a genuine attempt to build a new synthesis, aligning the established world picture with some of the new astronomical observations. The initiatory moves in these attempts, always made through a third party, ranged from the oblique to the overtly demanding.
As early as 1614 a group of Jesuits at Ingoldstadt saw problems in the way the new astronomical discoveries could be used by those interested in magic and astrology, and asked Aquaviva the General of the Society of Jesus to prohibit one of their members from writing in praise of Galileo's work. From this initial move against the Galilean findings, there stemmed a reactionary group which led to a reaffirmation of the primacy of the Aristotelian cosmology, in the Roman College in 1624.
With the Ludovisi Papacy, initiated by the election of Cardinal Ludovisi as Pope Gregory XV there emerged a lighter, more buoyant intellectual atmosphere, one in which Pope and Cardinal Nephew played a leading role. This change in Papal outlook caused Galileo to think there was the possibility that the severity of the 1616 Decree might be lessened, and as a consequence his long-promised book The Assayer was completed and appeared in manuscript early
in 1623. During the time of its printing Gregory XV died and
Maffeo Barberini became Urban VIII, and though this seemed to offer even better possibilities for Galileo, in the event there were to be greater problems ahead
A Multi Antenna Receiver for Galileo SoL Applications
No full textOne of the main features of the Galileo Satellite Navigation System is integrity. To ensure a reliable and robust navigation for Safety of Life applications, like CAT III aircraft landings, new receiver technologies are indispensable. Therefore, the German Aerospace Centre originated the development of a complete safety-of-life Galileo receiver to demonstrate the capabilities of new digital beam-forming and signal-processing algorithms for the detection and mitigation of interference. To take full advantage of those algorithms a carefully designed analogue signal processing is needed. The development addresses several challenging questions in the field of antenna design, frontend development and digital signal processing. The paper will give an insight in the activity and will present latest results
Accuracy Study of a Single Frequency Receiver Using a Combined GPS/GALILEO Constellation
No full textAs the date of availability of GALILEO approaches,
more and more interest appears to pre-evaluate the accuracy
of GALILEO and combined GPS+ GALILEO receivers.
The majority of simulations made are based on the
general use of UERE (often presented as a function of the
elevation angle of the satellite) multiplied by the GDOP
(Geometric Dilution Of Precision) matrix. This is a too
approximate approach to state for the real position error
distributions. Therefore, the concept of an Instantaneous
Pseudo Range Error (IPRE) is defined and is implemented
into NAVSIM the DLR’s end to end GNSS simulator. This
new module coupled with the other modules of the simulator
permit to lead complete End-to-End simulations. This
new functionality has the advantage to augment the field of
applications and to couple the generation of errors already
implemented in NAVSIM with error distributions coming
from real measurements. This study is a good first approach
to compare constellations between each other regarding
the accuracy issue. The IPRE concept multiplies
the functionalities thanks to its ability to generate real distributions
of errors. The application to a combined existing
constellation (GPS) for which real measurements can
be used with a not yet existing constellation (GALILEO)
for which only simulated data can be used is an interesting
approach. These results can directly be used to test the
impact of correction models, of filtering techniques, of antenna
types to a combined GPS/GALILEO system thanks
to the time series of IPRE and the instantaneous individual
errors output from NAVSIM. The best strategy of error mitigation
technique can be tested and the result can be used
for receiver design before the launch of GALILEO system
Design and Test of Beamforming Networks for a Galileo Antenna Array
No full textThe aim of the work is the design of a series of passive feeding networks that will steer the main beam of a Galileo antenna into different fixed directions to evaluate the performance of the array under such conditions
RAIM Algorithms Analysis for a Combined GPS/GALILEO Constellation
No full textHow far a user can rely on his navigation system is
a central question for safety of life applications like air
navigation especially in approach phases. For Oceanic,
En route or Non Precision Approach phases, the integrity
requirements as defined by the ICAO (International Civil
Aviation Organization) should be fulfilled by the future
Galileo Safety of Life Service.
This paper presents the performances of RAIM algorithms
using a covariance matrix of a single frequency absolute
positioning receiver noise calculated using one year
measurement data.
In the configuration of combined GPS/GALILEO constellation,
the user will have the possibility to track at
least 10 satellites at the same time. This high availability
of satellites will provide a high availability of RAIM
algorithms.
The original approach used in this paper is to use the IPRE
(Instantaneous Pseudo Range Error) developed in [1] as
the input parameter of the RAIM algorithms. This concept
provides a generalized covariance matrix of pseudo range
noise taking into account correlations of pseudo range
errors with close elevation and azimuth angles. Thanks
to a Cholesky decomposition, it is always possible to use
the classical χ2 distribution to obtain the fault detection
threshold. The advantage of generalizing the RAIM
methods is not only in the simplicity of the algorithm, but
it is also in its efficiency thanks to lower protection levels
obtained
Absolute Calibration of Dual Frequency Timing Receivers for Galileo
No full textThe timing service of Global Navigation Satellite Systems (GNSS) is being steadily improved. Generally, this fact traces back to increasing accuracy of the provided ephemeris data, improvements in Precise Point Positioning, continuous refinement of time transfer techniques, the utilization of modern signals, the use of wider bandwidth, and a growing number of available satellites—the latter particularly due to the coexistence of an increasing number of independent GNSSs available. The accuracy achievable by the GNSS common view time transfer method is within range of nanoseconds. In particular the upcoming Galileo in combination with the Global Positioning System is expected to improve that accuracy even further. In this paper, we present results for an approach for absolute calibration of Galileo timing receivers operating in the L1BC and E5 signal bands. The internal receiver delays for Galileo E1 and GPS L1 signals of the institute’s Septentrio PolaRx4 TR PRO are assessed. The approach utilizes a hardware simulator, which is an expanded version of a GSS7790 GNSS simulator from Spirent Communications. The simulator, the receiver under test, as well as the utilized measurement equipment use the 10 MHz signal from the same cesium clock as reference
Beamforming analysis on a broadband antenna array for the Galileo system
No full textThe objective of this work is to demonstrate, through simulation results, an optimized beamforming approach on an antenna array designed to operate at the Galileo frequency bands. In order to achieve this, a newly designed antenna element, which covers the whole Galileo frequency band, i.e. about 31% bandwidth, is employed. This element presents very good radiation characteristics like polarization purity and gain over a large range of scanning angles showing at the same time a reasonably good impedance matching. A 4 x 4 element antenna array is then designed with this antenna element and several simulations are performed. A beamforming algorithm developed whitin the DLR antenna group called Seqar is employed in order to calculate the optimized excitation current weights to be used by the antenna array. Finally, some results comparing the beamforming performance of the antenna array at the frequency band extremities are given and discussed
La primogenita di Galileo Galilei rivelata dalle sue lettere edite ed inedite;
No full textVita di Galileo e di sua figlia.--Lettere di suor Maria Celeste dirette a Galileo Galilei ... dal dì 10 maggio 1623 al dì 10 dicembre 1633.Mode of access: Internet
Le ragioni del patronage: i Farnese di Roma e Galileo
No full textIntervento al Convegno Il caso Galileo : una rilettura storica, filosofica, teologic
Opere di Galileo Galilei divise in quattro tomi : tomo primo
No full textMención de edición precede a título dependienteSign.: a4, A-44, 4T2Port. a dos tintas con marca tipográficaTexto con apostillas marginales e frisos e iniciales xilLas h. de grab. calc.: "F. Zucchi sculp.", son retrato de Galileo y fig. geométricas Las il. xil. son fig. geométricas y diagramasA 212/05
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