2,272 research outputs found
MBSE Certification-Driven Design of a UAV MALE Configuration in the AGILE 4.0 Design Environment
This paper presents a certification-driven design process for an Unmanned Medium-Altitude-
Long-Endurance (UAV MALE) air vehicle, including on-board system design and placements,
electro-magnetic compatibility analysis, and thermal risk assessments. In literature, the
preliminary aircraft design phase is mainly driven by mission performances and structural
integrity aspects. However, the inclusion of other disciplines, like on-board system design or
electro-magnetic compatibility, or thermal analysis, can lead to more efficient and cost-
effective solutions and becomes paramount for non-conventional configurations like
unmanned vehicles or highly electrified platforms. In the EC-funded AGILE 4.0 project
(2019-2022), the traditional scope of the preliminary aircraft design is extended by including
domains that are usually considered only in later design phases, such as certification,
production and maintenance. In this paper, the AGILE 4.0 design environment supports the
definition and execution of a certification-driven design process of a UAV MALE
configuration, using a Model-Based Systems Engineering (MBSE) approach
Microscopic Calculation of the Constitutive Relations
Homogenization theory is used to calculate the macroscopic dielectric
constant from the quantum microscopic dielectric function in a periodic medium.
The method can be used to calculate any macroscopic constitutive relation, but
it is illustrated here for the case of electrodynamics of matter. The so-called
cell problem of homogenization theory is solved and an explicit expression is
given for the macroscopic dielectric constant in a form akin to the
Clausius-Mossotti or Lorentz-Lorenz relation. The validity of this expression
is checked by showing that the macroscopic dielectric constant is causal and
has the expected symmetry properties, and that the average of the microscopic
energy density is the macroscopic one. Finally, the general expression is
applied to Bloch eigenstates. Finally, the corresponding many-body problem is
briefly discussed.Comment: 14 pages, 2 figure
Magnetic and chemical nonuniformity in Ga[1-x]Mn[x]As films as probed by polarized neutron and x-ray reflectometry
We have used complementary neutron and x-ray reflectivity techniques to
examine the depth profiles of a series of as-grown and annealed Ga[1-x]Mn[x]As
thin films. A magnetization gradient is observed for two as-grown films and
originates from a nonuniformity of Mn at interstitial sites, and not from local
variations in Mn at Ga sites. Furthermore, we see that the depth-dependent
magnetization can vary drastically among as-grown Ga[1-x]Mn[x]As films despite
being deposited under seemingly similar conditions. These results imply that
the depth profile of interstitial Mn is dependent not only on annealing, but is
also extremely sensitive to initial growth conditions. We observe that
annealing improves the magnetization by producing a surface layer that is rich
in Mn and O, indicating that the interstitial Mn migrates to the surface.
Finally, we expand upon our previous neutron reflectivity study of
Ga[1-x]Mn[x]As, by showing how the depth profile of the chemical composition at
the surface and through the film thickness is directly responsible for the
complex magnetization profiles observed in both as-grown and annealed films.Comment: Now Published in Physical Review
Therapeutic Vaccination Refocuses T-cell Responses Towards Conserved Regions of HIV-1 in Early Treated Individuals (BCN 01 study)
Background Strong and broad antiviral T-cell responses targeting vulnerable sites of HIV-1 will likely be a critical component for any effective cure strategy. Methods BCN01 trial was a phase I, open-label, non-randomized, multicenter study in HIV-1-positive individuals diagnosed and treated during early HIV-1 infection to evaluate two vaccination regimen arms, which differed in the time (8 versus 24 week) between the ChAdV63.HIVconsv prime and MVA.HIVconsv boost vaccinations. The primary outcome was safety. Secondary endpoints included frequencies of vaccine-induced IFN-γ+ CD8+ T cells, in vitro virus-inhibitory capacity, plasma HIV-1 RNA and total CD4+ T-cells associated HIV-1 DNA. (NCT01712425). Findings No differences in safety, peak magnitude or durability of vaccine-induced responses were observed between long and short interval vaccination arms. Grade 1/2 local and systemic post-vaccination events occurred in 22/24 individuals and resolved within 3 days. Weak responses to conserved HIV-1 regions were detected in 50% of the individuals before cART initiation, representing median of less than 10% of their total HIV-1-specific T cells. All participants significantly elevated these subdominant T-cell responses, which after MVA.HIVconsv peaked at median (range) of 938 (73-6,805) IFN-γ SFU/106 PBMC, representing on average 58% of their total anti-HIV-1 T cells. The decay in the size of the HIV-1 reservoir was consistent with the first year of early cART initiation in both arms
Search for supersymmetry with a dominant R-parity violating LQDbar couplings in e+e- collisions at centre-of-mass energies of 130GeV to 172 GeV
A search for pair-production of supersymmetric particles under the assumption
that R-parity is violated via a dominant LQDbar coupling has been performed
using the data collected by ALEPH at centre-of-mass energies of 130-172 GeV.
The observed candidate events in the data are in agreement with the Standard
Model expectation. This result is translated into lower limits on the masses of
charginos, neutralinos, sleptons, sneutrinos and squarks. For instance, for
m_0=500 GeV/c^2 and tan(beta)=sqrt(2) charginos with masses smaller than 81
GeV/c^2 and neutralinos with masses smaller than 29 GeV/c^2 are excluded at the
95% confidence level for any generation structure of the LQDbar coupling.Comment: 32 pages, 30 figure
First narrow-band search for continuous gravitational waves from known pulsars in advanced detector data
Spinning neutron stars asymmetric with respect to their rotation axis are potential sources of
continuous gravitational waves for ground-based interferometric detectors. In the case of known pulsars a
fully coherent search, based on matched filtering, which uses the position and rotational parameters
obtained from electromagnetic observations, can be carried out. Matched filtering maximizes the signalto-
noise (SNR) ratio, but a large sensitivity loss is expected in case of even a very small mismatch
between the assumed and the true signal parameters. For this reason, narrow-band analysis methods have
been developed, allowing a fully coherent search for gravitational waves from known pulsars over a
fraction of a hertz and several spin-down values. In this paper we describe a narrow-band search of
11 pulsars using data from Advanced LIGO’s first observing run. Although we have found several initial
outliers, further studies show no significant evidence for the presence of a gravitational wave signal.
Finally, we have placed upper limits on the signal strain amplitude lower than the spin-down limit for 5 of
the 11 targets over the bands searched; in the case of J1813-1749 the spin-down limit has been beaten for
the first time. For an additional 3 targets, the median upper limit across the search bands is below the
spin-down limit. This is the most sensitive narrow-band search for continuous gravitational waves carried
out so far
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