294 research outputs found
Foreign Military Sales: A historical review of Argentina\u27s purchases
Since June 1986 the Argentina Air Force maintains at WPAFB Ohio a procurement office to obtain defense articles under the Foreign Military Sales system. The aim of this thesis is to provide an historical review (1994-2012) of the procurement under FMS and bring some visibility about the procedures and get some managing indicators. The analysis considered three different aspects: the characteristics of the acquisition processes, the time in the procurement system and the relationships between independent variables and the acquisition time through a multivariate linear regression model. The results of the analyses are as follows: the USAF Services has the shortest procurement time, 78% of all acquisition processes initiated resulted in a 92% of fill rate; 68% of all acquisitions were considered Standard; and for both Standard and Non Standard the acquisition median delivery time was around a year. Also, neither the type of the defense article, type of procurements or the U.S. Service supplier influenced the pipeline time. Only the country priority showed a slight degree of linear association with time. The multivariate regression model had an R2 equal to 0.169, showing a weak linear association between variables
Monuments to the Confederacy and the Right to Destroy in Cultural-Property Law
This Note identifies problems in cultural-property law that the recent wave of removals of Confederate memorials has illustrated. Because cultural-property law’s internal logic tends inexorably towards supporting preservation, it has no conceptual framework for recognizing when a culture might be justified in destroying its own cultural property. I argue that destruction of cultural property can, in some cases, serve values that the preservationist impulse of cultural-property law has overlooked. I propose a new regime for cultural-property law that permits destruction in cases where the monument in question was established in celebration of a violation of the customary international law of human rights
Exceptional Judgments: Revising the Terrorism Exception to the Foreign Sovereign Immunities Act
In 2016, family members of victims of the September 11 terrorist attacks sued Iran in the Southern District of New York for aiding and abetting al Qaeda in the perpetration of those attacks. They proceeded under the terrorism exception to foreign sovereign immunity, which allows plaintiffs to sue foreign nations appearing on the State Department\u27s list of state sponsors of terrorism. When Iran failed to appear in court, a judge awarded the class a default judgment of 50 billion in default judgments of this kind
The MICADO project and its possible upgrades
The radiologic characterization is a very important step in dealing with materials and waste streams generated during operational and decommissioning phases of nuclear installations. Its goal is to determine the waste package radiologic content differenting between materials that can be released from regulatory con- trol and those that require further treatment and conditioning to become a stable waste form suitable for future storage and final disposal, according to its classifica- tion. Characterization is also needed in the pre-disposal stages of radioactive waste management to demonstrate compliance with the waste acceptance criteria of the storage facilities. This work presents the strategies developed and implemented by the MICADO EU project for an in-depth and accurate waste characterization and investigation of the different radioactive waste packages considered. It presents its goals, the methods developed and the technologies used contributing to the improve- ment of the safety. Special emphasis will also be given to complementary approaches highlighting the usability of the technologies and the digitalization and accessibility of the data
Retrieval of daytime mesospheric ozone using OSIRIS observations of O2 (a1Δg) emission
This work is distributed under the Creative Commons Attribution 4.0 License. Improving knowledge of the ozone global distributions in the mesosphere-lower thermosphere (MLT) is a crucial step in understanding the behaviour of the middle atmosphere. However, the concentration of ozone under sunlit conditions in the MLT is often so low that its measurement requires instruments with very high sensitivity. Fortunately, the bright oxygen airglow can serve as a proxy to retrieve the daytime ozone density indirectly, due to the strong connection to ozone photolysis in the Hartley band. The OSIRIS IR imager (hereafter, IRI), one of the instruments on the Odin satellite, routinely measures the oxygen infrared atmospheric band (IRA band) at 1.27 μm. In this paper, we will primarily focus on the detailed description of the steps done for retrieving the calibrated IRA band limb radiance (with <10 % random error), the volume emission rate of O2 (a1i"g) (with <25 % random error) and finally the ozone number density (with <20 % random error). This retrieval technique is applied to a 1-year sample from the IRI dataset. The resulting product is a new ozone dataset with very tight along-track sampling distance (<20 km). The feasibility of the retrieval technique is demonstrated by a comparison of coincident ozone measurements from other instruments aboard the same spacecraft, as well as zonal mean and monthly average comparisons between Odin-OSIRIS (both spectrograph and IRI), Odin-SMR and Envisat-MIPAS. We find that IRI appears to have a positive bias of up to 25 % below 75 km, and up to 50 % in some regions above. We attribute these differences to uncertainty in the IRI calibration as well as uncertainties in the photochemical constants. However, the IRI ozone dataset is consistent with the compared dataset in terms of the overall atmospheric distribution of ozone between 50 and 100 km. If the origin of the bias can be identified before processing the entire dataset, this will be corrected and noted in the dataset description. The retrieval technique described in this paper can be further applied to all the measurements made throughout the 19 year mission, leading to a new, long-term high-resolution ozone dataset in the middle atmosphere
The OH (3-1) nightglow volume emission rate retrieved from OSIRIS measurements: 2001 to 2015
The OH airglow has been used to investigate the chemistry and dynamics of the mesosphere and the lower thermosphere (MLT) for a long time. The infrared imager (IRI) aboard the Odin satellite has been recording the night-time 1.53 mu m OH (3-1) emission for more than 15 years (2001-2015), and we have recently processed the complete data set. The newly derived data products contain the volume emission rate profiles and the Gaussian-approximated layer height, thickness, peak intensity and zenith intensity, and their corresponding error estimates. In this study, we describe the retrieval steps for these data products. We also provide data screening recommendations. The monthly zonal averages depict the well-known annual oscillation and semi-annual oscillation signatures, which demonstrate the fidelity of the data set (https://doi.org/10.5281/zenodo.4746506, Li et al., 2021). The uniqueness of this Odin IRI OH long-term data set makes it valuable for studying various topics, for instance, the sudden stratospheric warming events in the polar regions and solar cycle influences on the MLT
Projected SO(5) Hamiltonian for Cuprates and Its Applications
The projected SO(5) (pSO(5)) Hamiltonian incorporates the quantum spin and
superconducting fluctuations of underdoped cuprates in terms of four bosons
moving on a coarse grained lattice. A simple mean field approximation can
explain some key feautures of the experimental phase diagram: (i) The Mott
transition between antiferromagnet and superconductor, (ii) The increase of T_c
and superfluid stiffness with hole concentration x and (iii) The increase of
antiferromagnetic resonance energy as sqrt{x-x_c} in the superconducting phase.
We apply this theory to explain the ``two gaps'' problem found in underdoped
cuprate Superconductor-Normal- Superconductor junctions. In particular we
explain the sharp subgap Andreev peaks of the differential resistance, as
signatures of the antiferromagnetic resonance (the magnon mass gap). A critical
test of this theory is proposed. The tunneling charge, as measured by shot
noise, should change by increments of Delta Q= 2e at the Andreev peaks, rather
than by Delta Q=e as in conventional superconductors.Comment: 3 EPS figure
An efficient method for the incompressible Navier-Stokes equations on irregular domains with no-slip boundary conditions, high order up to the boundary
Common efficient schemes for the incompressible Navier-Stokes equations, such
as projection or fractional step methods, have limited temporal accuracy as a
result of matrix splitting errors, or introduce errors near the domain
boundaries (which destroy uniform convergence to the solution). In this paper
we recast the incompressible (constant density) Navier-Stokes equations (with
the velocity prescribed at the boundary) as an equivalent system, for the
primary variables velocity and pressure. We do this in the usual way away from
the boundaries, by replacing the incompressibility condition on the velocity by
a Poisson equation for the pressure. The key difference from the usual
approaches occurs at the boundaries, where we use boundary conditions that
unequivocally allow the pressure to be recovered from knowledge of the velocity
at any fixed time. This avoids the common difficulty of an, apparently,
over-determined Poisson problem. Since in this alternative formulation the
pressure can be accurately and efficiently recovered from the velocity, the
recast equations are ideal for numerical marching methods. The new system can
be discretized using a variety of methods, in principle to any desired order of
accuracy. In this work we illustrate the approach with a 2-D second order
finite difference scheme on a Cartesian grid, and devise an algorithm to solve
the equations on domains with curved (non-conforming) boundaries, including a
case with a non-trivial topology (a circular obstruction inside the domain).
This algorithm achieves second order accuracy (in L-infinity), for both the
velocity and the pressure. The scheme has a natural extension to 3-D.Comment: 50 pages, 14 figure
NRLMSIS 2.1: An Empirical Model of Nitric Oxide Incorporated Into MSIS
We have developed an empirical model of nitric oxide (NO) number density at altitudes from similar to 73 km to the exobase, as a function of altitude, latitude, day of year, solar zenith angle, solar activity, and geomagnetic activity. The model is part of the NRLMSIS (R) 2.1 empirical model of atmospheric temperature and species densities; this upgrade to NRLMSIS 2.0 consists solely of the addition of NO. MSIS 2.1 assimilates observations from six space-based instruments: UARS/HALOE, SNOE, Envisat/MIPAS, ACE/FTS, Odin/SMR, and AIM/SOFIE. We additionally evaluated the new model against independent extant NO data sets. In this paper, we describe the formulation and fitting of the model, examine biases between the data sets and model and among the data sets, compare with another empirical NO model (NOEM), and discuss scientific aspects of our analysis
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