9,642 research outputs found
The Safe-Port project: an approach to port surveillance and protection
SAFE-PORT is a recently started project addressing the complex issue of determining the best configurations of resources for harbour and port surveillance and protection. More specifically, the main goal is to find, for any given scenario, an adequate set of configuration solutions — i.e., number and type of sensors and equipments, their locations and operating modes, the corresponding personnel and other support resources — that maximize protection over a specific area.
The project includes research and development of sensors models, novel algorithms for optimization and decision support, and a computer-based decision support system (DSS) to assist decision makers in that task. It includes also the development of a simulation environment for modelling relevant aspects of the scenario (including sensors used for surveillance, platforms, threats and the environment), capable to incorporate data from field-trials, used to test and validate solutions proposed by the DSS. Test cases will consider the use of intelligent agents to model the behaviour of threats and of NATO forces in a realistic way, following experts’ definitions and parameters
Spin torque ferromagnetic resonance with magnetic field modulation
We demonstrate a technique of broadband spin torque ferromagnetic resonance
(ST-FMR) with magnetic field modulation for measurements of spin wave
properties in magnetic nanostructures. This technique gives great improvement
in sensitivity over the conventional ST-FMR measurements, and application of
this technique to nanoscale magnetic tunnel junctions (MTJs) reveals a rich
spectrum of standing spin wave eigenmodes. Comparison of the ST-FMR
measurements with micromagnetic simulations of the spin wave spectrum allows us
to explain the character of low-frequency magnetic excitations in nanoscale
MTJs.Comment: Also see: http://faculty.sites.uci.edu/krivorotovgroup
No-horizon theorem for spacetimes with spacelike G1 isometry groups
We consider four-dimensional spacetimes which obey the
Einstein equations , and admit a global spacelike
isometry group. By means of dimensional reduction and local
analyis on the reduced (2+1) spacetime, we obtain a sufficient condition on
which guarantees that cannot contain apparent
horizons. Given any (3+1) spacetime with spacelike translational isometry, the
no-horizon condition can be readily tested without the need for dimensional
reduction. This provides thus a useful and encompassing apparent horizon test
for -symmetric spacetimes. We argue that this adds further evidence
towards the validity of the hoop conjecture, and signals possible violations of
strong cosmic censorship.Comment: 8 pages, LaTeX, uses IOP package; published in Class. Quantum Gra
Gluon saturation and the Froissart bound: a simple approach
At very high energies we expect that the hadronic cross sections satisfy the
Froissart bound, which is a well-established property of the strong
interactions. In this energy regime we also expect the formation of the Color
Glass Condensate, characterized by gluon saturation and a typical momentum
scale: the saturation scale . In this paper we show that if a saturation
window exists between the nonperturbative and perturbative regimes of Quantum
Chromodynamics (QCD), the total cross sections satisfy the Froissart bound.
Furthermore, we show that our approach allows us to describe the high energy
experimental data on total cross sections.Comment: 6 pages, 5 figures. Includes additional figures, discussion and
reference
Improving cost-efficiency for MPs density separation by zinc chloride reuse
The methodology used to extract and quantify microplastics (MPs) in aquatic systems are still not standardized. Salt saturated solutions, such as sodium chloride (NaCl), zinc chloride (ZnCl2) and/or sodium iodide (NaI), are normally added to separate dense plastics from aquatic samples. However, the most effective reagents are also the most expensive (e.g. ZnCl2 and NaI). To decrease this cost, a reuse process of the salt solutions should be applied. The reuse process has been widely investigated for the NaI solution neglecting the ZnCl2. Hence, the aim of this study was to present a simple methodology to reuse the ZnCl2 solution ensuring the efficiency of the product. Results of the present study showed that ZnCl2 solution could be reused at least five times maintaining an efficiency above 95 %. •The ZnCl2 reuse decreases the cost of the methodology.•The efficiency of ZnCl2 solution after five filtrations remains above 95 % (all polymers are detected and recovered).•The use of this salt solution is the most cost-effective methodology to isolate MPs from aquatic samples.publishe
Phase diagram of a random-anisotropy mixed-spin Ising model
We investigate the phase diagram of a mixed spin-1/2--spin-1 Ising system in
the presence of quenched disordered anisotropy. We carry out a mean-field and a
standard self-consistent Bethe--Peierls calculation. Depending on the amount of
disorder, there appear novel transition lines and multicritical points. Also,
we report some connections with a percolation problem and an exact result in
one dimension.Comment: 8 pages, 4 figures, accepted for publication in Physical Review
Marine Biodiversity and Ecosystem Health of Ilhas Selvagens, Portugal
In September 2015, National Geographic's Pristine Seas project, in conjunction with the Instituto Universitário-Portugal, The Waitt Institute, the University of Western Australia, and partners conducted a comprehensive assessment of the rarely surveyed Ilhas Selvagens to explore the marine environment, especially the poorly understood deep sea and open ocean areas, and quantify the biodiversity of the nearshore marine environment
Magnetic phase transitions in Ta/CoFeB/MgO multilayers
We study thin films and magnetic tunnel junction nanopillars based on
Ta/CoFeB/MgO multilayers by electrical transport and
magnetometry measurements. These measurements suggest that an ultrathin
magnetic oxide layer forms at the CoFeB/MgO interface. At
approximately 160 K, the oxide undergoes a phase transition from an insulating
antiferromagnet at low temperatures to a conductive weak ferromagnet at high
temperatures. This interfacial magnetic oxide is expected to have significant
impact on the magnetic properties of CoFeB-based multilayers used in spin
torque memories
Self-assembled nanoparticles made of dextrin
The amphiphilic molecule dextrin-VA-SC16 (dexC16) was produced and studied in this work. DexC16 has a hydrophilic dextrin backbone with grafted acrylate groups (VA), substituted with hydrophobic 1- exadecanethiol (C16). The dextrin degree of substitution with the hydrophobic chains (DSC16, number of alkyl chains per 100 dextrin glucopyranoside residues) may be controlled. Materials with different DSC16 were prepared and characterized using ¹H NMR. DexC16 self assembles in water through association of the hydrophobic alkyl chains, originating hydrogel nanoparticles. The properties of the hydrogel nanoparticle were studied by dynamic light scattering (DLS), fluorescence spectroscopy and atomic force microscopy (AFM)
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