312 research outputs found

    Asymmetric fundamental band CO lines as a sign of an embedded giant planet

    Get PDF
    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

    Get PDF
    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

    Get PDF
    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

    Get PDF
    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

    Get PDF
    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

    Get PDF
    It is well-known that if a real valued function acting on a convex set satisfies the nn-variable Jensen inequality, for some natural number n2n\geq 2, then, for all k{1,,n}k\in\{1,\dots, n\}, it fulfills the kk-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 (M,N)(M,N)-convexity property of functions and also for H\"older--Minkowski type inequalities
    corecore