312 research outputs found
Asymmetric fundamental band CO lines as a sign of an embedded giant planet
We investigate the formation of double-peaked asymmetric line profiles of CO
in the fundamental band spectra emitted by young (1-5Myr) protoplanetary disks
hosted by a 0.5-2 Solar mass star. Distortions of the line profiles can be
caused by the gravitational perturbation of an embedded giant planet with q=4.7
10^-3 stellar-to-planet mass ratio. Locally isothermal, 2D hydrodynamic
simulations show that the disk becomes globally eccentric inside the planetary
orbit with stationary ~0.2-0.25 average eccentricity after ~2000 orbital
periods. For orbital distances 1-10 AU, the disk eccentricity is peaked inside
the region where the fundamental band of CO is thermal excitated. Hence, these
lines become a sensitive indicators of the embedded planet via their
asymmetries (both in flux and wavelength). We find that the line shape
distortions (e.g. distance, central dip, asymmetry and positions of peaks) of a
given transition depend on the excitation energy (i.e. on the rotational
quantum number J). The magnitude of line asymmetry is increasing/decreasing
with J if the planet orbits inside/outside the CO excitation zone (R_CO<=3, 5
and 7 AU for a 0.5,1 and 2 Solar mass star, respectively), thus one can
constrain the orbital distance of a giant planet by determining the slope of
peak asymmetry-J profile. We conclude that the presented spectroscopic
phenomenon can be used to test the predictions of planet formation theories by
pushing the age limits for detecting the youngest planetary systems.Comment: 7 pages, 5 figures, to appear in ApJ
Improving Link Reliability through Network Coding in Cooperative Cellular Networks
The paper proposes a XOR-based network coded cooperation protocol for the uplink transmission of relay assisted cellular networks and an algorithm for selection and assignment of the relay nodes. The performances of the cooperation protocol are expressed in terms of network decoder outage probability and Block Error Rate of the cooperating users. These performance indicators are analyzed theoretically and by computer simulations. The relay nodes assignment is based on the optimization, according to several criteria, of the graph that describes the cooperation cluster formed after an initial selection of the relay nodes. The graph optimization is performed using Genetic Algorithms adapted to the topology of the cooperation cluster and the optimization criteria considered
NEW DATA ON THE EVALUATION OF THE INFRARED (IR) SPECTRA OF SUBSTANCES OF COMPLICATED STRUCTURE AND THEIR APPLICATION FOR IDENTIFICATION WITH PRIMA PATTERN RECOGNITION METHOD. PART I
In our paper the change in chemical composition was studied on samples (leaf, tendril-
flower, stem, complete plant) taken in a 2-week period (July 2-July 16) of the development of
tobacco plant, grown by two different modes of cultivation (bed and ensilage) with classical
analytical and infrared (IR) spectroscopic methods. IR spectra were evaluated by traditional
spectroscopic method and by pattern recognition method PRIMA (pattern Recognition by
Independent Multicategory Analysis). The intensity of the IR bands was used for our investiga-
tions, which was given in relative % value, introduced by us. Data needed for mathematical
processing were obtained by a new procedure, by feature selection resting on spectroscopical
basis.
The dependence of cellulose and total nitrogen content, further the intensity of the IR
spectral bands characteristic of these components, on the ripeness of the plant, on the quality
of the plant part, on the mode of cultivation and on the place of the leaf on the plant were
established. Various tobacco plant samples, having an identical IR spectrum on visual inspec-
tion, were separated and identified with the PRIMA pattern recognition method with a
recognition power between 97 and 100% according to their origin (ripeness, mode of cultiva-
tion quality, place on the plant)
Whey separation using TiO<sub>2</sub>-modified ultrafiltration membrane
Nowadays, the membrane filtration technique is a commonly used method for the separation of whey. The most significant limitation of membrane applications is fouling, which causes flux decline. During this work, regenerated cellulose membranes covered by TiO2-nanoparticles were investigated and applied to the separation of whey solution. Experiments were carried out in a dead-end ultrafiltration cell, and the changes in filtration parameters and the photocatalytic effects of the UV irradiated TiO2 modified membrane surface on the membrane fouling were examined. Our results showed that the water flux decreased with increasing TiO2 layer thickness, but the retention of turbidity and of COD increased. After separation, the membrane surface was cleaned by UV irradiation by means of photocatalytic oxidation. It was found that the original flux was recoverable, while the retention of the membrane decreased after cleaning
How important is the Family? : Alpha nuclear potentials and p-process nucleosynthesis
Copyright owned by the author(s) under the terms of the Creative Commons Attribution-NonCommercial-ShareAlike LicenceIn this work we present the results from the analysis of the experimentally measured angular distributions of the reaction 106Cd(α , α )106 Cd at several different energies around the Coulomb barrier. The difficulties that arise in the study of 106Cd-α -nuclear potential and the so called Family Problem are addressed in this work
Reducible means and reducible inequalities
It is well-known that if a real valued function acting on a convex set
satisfies the -variable Jensen inequality, for some natural number , then, for all , it fulfills the -variable Jensen
inequality as well. In other words, the arithmetic mean and the Jensen
inequality (as a convexity property) are both reducible. Motivated by this
phenomenon, we investigate this property concerning more general means and
convexity notions. We introduce a wide class of means which generalize the
well-known means for arbitrary linear spaces and enjoy a so-called reducibility
property. Finally, we give a sufficient condition for the reducibility of the
-convexity property of functions and also for H\"older--Minkowski type
inequalities
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