65,002 research outputs found
Testing device subjects elastic materials to biaxial deformations
Testing device stretches elastic materials biaxially over large deformation ranges and varies strain ratios in two perpendicular directions. The device is used in conjunction with a tensile testing machine, which holds the specimen and permits control over the direction and magnitude of the stresses applied
Comparison of the INRIM and PTB lattice-spacing standards
To base the kilogram definition on the atomic mass of the silicon 28 atom,
the present relative uncertainty of the silicon 28 lattice parameter must
lowered to 3E-9. To achieve this goal, a new experimental apparatus capable of
a centimetre measurement-baseline has been made at the INRIM. The comparison
between the determinations of the lattice parameter of crystals MO*4 of INRIM
and WASO4.2a of PTB is intended to verify the measurement capabilities and to
assess the limits of this experiment.Comment: 10 pages, 8 figures, submitted to Metrologi
Detection of X-ray Emission from the Very Old Pulsar J0108-1431
PSR J0108-1431 is a nearby, 170 Myr old, very faint radio pulsar near the
"pulsar death line" in the P-Pdot diagram. We observed the pulsar field with
the Chandra X-ray Observatory and detected a point source (53 counts in a 30 ks
exposure, energy flux (9+/-2)\times 10^{-15} ergs cm^{-2} s^{-1} in the 0.3-8
keV band) close to the radio pulsar position. Based on the large X-ray/optical
flux ratio at the X-ray source position, we conclude that the source is the
X-ray counterpart of PSR J0108-1431.The pulsar spectrum can be described by a
power-law model with photon index Gamma \approx 2.2 and luminosity L_{0.3-8
keV} \sim 2\times 10^{28} d_{130}^2 ergs s^{-1}, or by a blackbody model with
the temperature kT\approx 0.28 keV and bolometric luminosity L_{bol} \sim
1.3\times 10^{28} d_{130}^2 ergs s^{-1}, for a plausible hydrogen column
density NH = 7.3\times 10^{19} cm^{-2} (d_{130}=d/130 pc). The pulsar converts
\sim 0.4% of its spin-down power into the X-ray luminosity, i.e., its X-ray
efficiency is higher than for most younger pulsars. From the comparison of the
X-ray position with the previously measured radio positions, we estimated the
pulsar proper motion of 0.2 arcsec yr^{-1} (V_\perp \sim 130 d_{130} km
s^{-1}), in the south-southeast direction.Comment: 8 pages, 9 figures, accepted to ApJ; minor revisions in Sections 2.2
and 3.
Autonomous Spacecraft Navigation With Pulsars
An external reference system suitable for deep space navigation can be
defined by fast spinning and strongly magnetized neutron stars, called pulsars.
Their beamed periodic signals have timing stabilities comparable to atomic
clocks and provide characteristic temporal signatures that can be used as
natural navigation beacons, quite similar to the use of GPS satellites for
navigation on Earth. By comparing pulse arrival times measured on-board a
spacecraft with predicted pulse arrivals at a reference location, the
spacecraft position can be determined autonomously and with high accuracy
everywhere in the solar system and beyond. The unique properties of pulsars
make clear already today that such a navigation system will have its
application in future astronautics. In this paper we describe the basic
principle of spacecraft navigation using pulsars and report on the current
development status of this novel technology.Comment: 22 pages, 12 figures, 2 tables, to be published in the proceedings of
the workshop "Relativistic Positioning Systems and their Scientific
Applications", held on 19-21 Sept. 2012, Brdo near Kranj, Sloveni
A New Look at Economic Convergence in Europe: A Common Factor Approach
We propose a common factor approach to analyse convergence, which we implement using principal components analysis. We show that this method provides a useful new way of approaching the convergence debate. We apply this technique to a dataset of nominal and real monthly exchange rates of the twelve member countries of the European Monetary Union over the period 1970-2001. Our empirical results neatly capture the convergence patterns related to the various regimes from Bretton Woods toward EMU. The UK's Pound Sterling has been on a gradual convergence path to the Euro, although convergence is less progressed than it was for the EMU countries by 1999.Convergence, exchange rates, European Monetary Union, nominal convergence, real convergence, principal components analysis.
How Far From the Euro Area? Measuring Convergence of Inflation Rates in Eastern Europe
We present a common factor framework of convergence which we implement using principal components analysis. We apply this technique to a dataset of monthly inflation rates of EMU and the Eastern European New Member Countries (NMC) over 1996-2007. In the earlier years, the NMC rates moved independently from an average of the three best performing countries over the past twelve months, while they moved somewhat closer in line with them in the later years. Looking at the sample of the EMU and NMC countries as a whole, there is evidence of a formation of convergence clubs across the two groups.Convergence; inflation rates; European Monetary Union; principal components analysis
An Entrepreneurial Theory of Formal Organizations. Part I - Patterns of Formal Organizations
Theory of formal organizations with ordering of relevant dat
Measuring Convergence of the New Member Countries’ Exchange Rates to the Euro
We propose a common factor approach to analyse convergence, which we implement using principal components analysis. This technique has not been used to analyse convergence of time series but is shown to provide a useful new tool. We show how it is in many ways a more natural way of approaching the convergence debate. We apply these ideas to a dataset of bilateral Euro and US-Dollar exchange rates of the new member countries of the European Union. Our empirical application gives sensible results about the convergence process of the new member countries’ exchange rates to the Euro.Convergence; exchange rates; transition economies; principal components analysis
How Far From the Euro Area? Measuring Convergence of Inflation Rates in Eastern Europe
We present a common factor framework of convergence which we implement using principal components analysis. We apply this technique to a dataset of monthly inflation rates of EMU and the Eastern European New Member Countries (NMC) over 1996-2007. In the earlier years, the NMC rates moved independently from an average of the three best performing countries over the past twelve months, while they moved somewhat closer in line with them in the later years. Looking at the sample of the EMU and NMC countries as a whole, there is evidence of a formation of convergence clubs across the two groups.Convergence, inflation rates, European Monetary Union, principal components analysis.
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