3,396 research outputs found
ZnO- and TiO2-based nanostructures
Transition-metal oxide (TMO) nanostructures are the focus of current research efforts in nanotechnology since they are the most common minerals on Earth, and also thanks to their special shapes, compositions, and chemical and physical properties.[...]
Jensen Shannon divergence as a measure of the degree of entanglement
The notion of distance in Hilbert space is relevant in many scenarios. In
particular, distances between quantum states play a central role in quantum
information theory. An appropriate measure of distance is the quantum Jensen
Shannon divergence (QJSD) between quantum states. Here we study this distance
as a geometrical measure of entanglement and apply it to different families of
states.Comment: 5 pages, 2 figures, to appear in the special issue of IJQI "Noise,
Information and Complexity at Quantum Scale", eds. S. Mancini and F.
Marcheson
Granular flow in equilibrium with the bottom: experimental analysis and theoretical prediction
International audienceThe paper presents measurements performed on the granular flow that develops in a drum partially filled with sand grains and rotating at various speeds. The aims of the paper are: to provide experimental evidence and measurements on grain flow in a drum; to compare theoretical and experimental velocity profiles; to point out discrepancies among theory and experiments. Velocity and "temperature" profiles were obtained with a Laser Doppler Anemometer (LDA) in the mid-section of the stream, where the flow is usually uniform; image analysis and visual observations of the flow were also carried out to evaluate the local slope, the depths of the characteristic flow regions and the concentration of the granular material. A semi-empirical relation that fits the experimental velocity profiles is presented and compared with Takahashi's velocity distributions for rigid and erodible bed. As proven by the distributions of free surface elevation, velocity, volumetric concentration and grain size across the drum, the three-dimensional nature of the flow field is not negligible. By increasing the drum rotation speed, in correspondence with critical and supercritical flows, changes in the flow regime are observed with formation of quasi-stationary surface waves. Wave development is described by analysing the extension and form of the experimental and theoretical velocity profiles. Wave effects on measurements are quantified and checked comparing the free-surface velocity-discharge relation obtained from experiments and from Takahashi's model for erodible bed
Viewing the Steklov eigenvalues of the Laplace operator as critical Neumann eigenvalues
We consider the Steklov eigenvalues of the Laplace operator as limiting
Neumann eigenvalues in a problem of boundary mass concentration. We discuss the
asymptotic behavior of the Neumann eigenvalues in a ball and we deduce that the
Steklov eigenvalues minimize the Neumann eigenvalues. Moreover, we study the
dependence of the eigenvalues of the Steklov problem upon perturbation of the
mass density and show that the Steklov eigenvalues violates a maximum principle
in spectral optimization problems.Comment: This is a preprint version of a paper that will appear in the
Proceedings of the 9th ISAAC Congress, Krak\'ow 201
Wave simulation for the design of an innovative quay wall: the case of Vlorë Harbour
Sea states and environmental conditions are basic data for the
design of marine structures. Hindcasted wave data have been applied here
with the aim of identifying the proper design conditions for an innovative
quay wall concept.
In this paper, the results of a computational fluid dynamics model are used to
optimise the new absorbing quay wall of Vlorë Harbour (Republic of
Albania) and define the design loads under extreme wave
conditions. The design wave states at the harbour entrance have been
estimated analysing 31Â years of hindcasted wave data simulated through the
application of WaveWatch III. Due to the particular geography and topography
of the Bay of Vlorë, wave conditions generated from the north-west are
transferred to the harbour entrance with the application of a 2-D spectral wave
module, whereas southern wave states, which are also the most critical for
the port structures, are defined by means of a wave generation model,
according to the available wind measurements. Finally, the identified extreme
events have been used, through the NewWave approach, as boundary conditions
for the numerical analysis of the interaction between the quay wall and the
extreme events. The results show that the proposed method, based on
numerical modelling at different scales from macro to meso and to micro,
allows for the identification of the best site-specific solutions, also for a
location devoid of any wave measurement. In this light, the objectives of
the paper are two-fold. First, they show the application of sea condition
estimations through the use of wave hindcasted data in order to properly
define the design wave conditions for a new harbour structure. Second, they
present a new approach for investigating an innovative absorbing quay wall based
on CFD modelling and the NewWave theory
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