43,024 research outputs found

    Precipitation detector Patent

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    Precipitation detector and mechanism for stopping and restarting machinery at initiation and cessation of rai

    Disc wind models for FU Ori objects

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    We present disc wind models aimed at reproducing the main features of the strong Na I resonance line P-Cygni profiles in the rapidly-accreting pre-main sequence FU Ori objects. We conducted Monte Carlo radiative transfer simulations for a standard magnetocentrifugally driven wind (MHD) model and our own "Genwind" models, which allows for a more flexible wind parameterisation. We find that the fiducial MHD wind and similar Genwind models, which have flows emerging outward from the inner disc edge, and thus have polar cavities with no absorbing gas, cannot reproduce the deep, wide Na I absorption lines in FU Ori objects viewed at low inclination. We find that it is necessary to include an "inner wind" to fill this polar cavity to reproduce observations. In addition, our models assuming pure scattering source functions in the Sobolev approximation at intermediate viewing angles (30∘≲i≲60∘30^{\circ} \lesssim i \lesssim 60^{\circ}) do not yield sufficiently deep line profiles. Assuming complete absorption yields better agreement with observations, but simple estimates strongly suggest that pure scattering should be a much better approximation. The discrepancy may indicate that the Sobolev approximation is not applicable, possibly due to turbulence or non-monotonic velocity fields; there is some observational evidence for the latter. Our results provide guidance for future attempts to constrain FU Ori wind properties using full MHD wind simulations, by pointing to the importance of the boundary conditions necessary to give rise to an inner wind, and by suggesting that the winds must be turbulent to produce sufficiently deep line profiles.Comment: 12 pages, 17 figures, accepted for publication in MNRA

    Lipid changes within the epidermis of living skin equivalents observed across a time-course by MALDI-MS imaging and profiling

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    © 2015 Mitchell et al. Abstract Background: Mass spectrometry imaging (MSI) is a powerful tool for the study of intact tissue sections. Here, its application to the study of the distribution of lipids in sections of reconstructed living skin equivalents during their development and maturation is described. Methods: Living skin equivalent (LSE) samples were obtained at 14 days development, re-suspended in maintenance medium and incubated for 24 h after delivery. The medium was then changed, the LSE re-incubated and samples taken at 4, 6 and 24 h time points. Mass spectra and mass spectral images were recorded from 12 μm sections of the LSE taken at each time point for comparison using matrix assisted laser desorption ionisation mass spectrometry. Results: A large number of lipid species were identified in the LSE via accurate mass-measurement MS and MSMS experiments carried out directly on the tissue sections. MS images acquired at a spatial resolution of 50 μm × 50 μm showed the distribution of identified lipids within the developing LSE and changes in their distribution with time. In particular development of an epidermal layer was observable as a compaction of the distribution of phosphatidylcholine species. Conclusions: MSI can be used to study changes in lipid composition in LSE. Determination of the changes in lipid distribution during the maturation of the LSE will assist in the identification of treatment responses in future investigations

    Prime Factorization in the Duality Computer

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    We give algorithms to factorize large integers in the duality computer. We provide three duality algorithms for factorization based on a naive factorization method, the Shor algorithm in quantum computing, and the Fermat's method in classical computing. All these algorithms are polynomial in the input size.Comment: 4 page

    Evolution of Nuclear Shell Structure due to the Pion Exchange Potential

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    The evolution of nuclear shell structure is investigated for the first time within density-dependent relativistic Hartree-Fock theory and the role of π\pi-exchange potential is studied in detail. The energy differences between the neutron orbits \Lrb{\nu1h_{9/2},\nu 1i_{13/2}} in the N=82 isotones and between the proton ones \Lrb{\pi1g_{7/2},\pi1h_{11/2}} in the Z=50 isotopes are extracted as a function of neutron excess N−ZN-Z. A kink around Z=58Z = 58 for the N=82 isotones is found as an effect resulting from pion correlations. It is shown that the inclusion of π\pi-coupling plays a central role to provide realistic isospin dependence of the energy differences. In particular, the tensor part of the π\pi-coupling has an important effect on the characteristic isospin dependence observed in recent experiments.Comment: 4 pages and 4 figure

    The reverberation signatures of rotating disc winds in active galactic nuclei

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    The broad emission lines (BELs) in active galactic nuclei (AGN) respond to ionizing continuum variations. The time and velocity dependence of their response depends on the structure of the broad-line region: its geometry, kinematics and ionization state. Here, we predict the reverberation signatures of BELs formed in rotating accretion disc winds. We use a Monte Carlo radiative transfer and ionization code to predict velocity-delay maps for representative high- (C IV~IV) and low-ionization (Hα\alpha) emission lines in both high- and moderate-luminosity AGN. Self-shielding, multiple scattering and the ionization structure of the outflows are all self-consistently taken into account, while small-scale structure in the outflow is modelled in the micro-clumping approximation. Our main findings are: (1) The velocity-delay maps of smooth/micro-clumped outflows often contain significant negative responses. (2)~The reverberation signatures of disc wind models tend to be rotation dominated and can even resemble the classic "red-leads-blue" inflow signature. (3) Traditional "blue-leads-red" outflow signatures can usually only be observed in the long-delay limit. (4) Our models predict lag-luminosity relationships similar to those inferred from observations, but systematically underpredict the observed centroid delays. (5) The ratio between "virial product" and black hole mass predicted by our models depends on viewing angle. Our results imply that considerable care needs to be taken in interpreting data obtained by observational reverberation mapping campaigns. In particular, basic signatures such as "red-leads-blue", "blue-leads-red" and "blue and red vary jointly" are not always reliable indicators of inflow, outflow or rotation. This may help to explain the perplexing diversity of such signatures seen in observational campaigns to date.Comment: 15 pages, 17 figures, 2 tables. Accepted by MNRAS 20/7/201

    Energy Efficient User Association and Power Allocation in Millimeter Wave Based Ultra Dense Networks with Energy Harvesting Base Stations

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    Millimeter wave (mmWave) communication technologies have recently emerged as an attractive solution to meet the exponentially increasing demand on mobile data traffic. Moreover, ultra dense networks (UDNs) combined with mmWave technology are expected to increase both energy efficiency and spectral efficiency. In this paper, user association and power allocation in mmWave based UDNs is considered with attention to load balance constraints, energy harvesting by base stations, user quality of service requirements, energy efficiency, and cross-tier interference limits. The joint user association and power optimization problem is modeled as a mixed-integer programming problem, which is then transformed into a convex optimization problem by relaxing the user association indicator and solved by Lagrangian dual decomposition. An iterative gradient user association and power allocation algorithm is proposed and shown to converge rapidly to an optimal point. The complexity of the proposed algorithm is analyzed and the effectiveness of the proposed scheme compared with existing methods is verified by simulations.Comment: to appear, IEEE Journal on Selected Areas in Communications, 201

    Finite element modelling of material deformation and damage by tension under cyclic bending and compression test

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    Material deformation is determined by strain and stress states resulted from loading conditions applied on the material during the manufacturing process. Different testing methods, for example, uniaxial tensile test and dome test have been used to predict material deformation behavior during the manufacturing processes. However, under a complex deformation mode, materials display distinct deformation behavior. In double side incremental forming (DSIF) process, it has been widely acknowledged that the material deformation consists of stretching, bending, shearing, compression with cyclic loading. This leads to a significant material formability enhancement comparing to conventional sheet metal forming processes. This phenomenon cannot be explained by using the currently available testing methods because the complexity of the DSIF process prohibits a direct investigation of the influence of individual deformation modes. To simplify the loading conditions and to investigate their individual and interactive effects contributing to the formability enhancement in DSIF, in this study, a novel testing method of Tension under Cyclic Bending and Compression (TCBC) is proposed, through which the effect of stretching, bending, compression and cyclic loading can be independently evaluated. A finite element (FE) damage modelling of the TCBC test was developed by incorporating the shear-modified Gurson-Tvergaard-Needleman (GTN) model into the Abaqus/Explicit solver. The results showed that the damage accumulation in the material was suppressed due to the localized and cyclic material deformation. An enhanced material formability was obtained by using the FE damage modelling and the periodical accumulation of the damage showed that the TCBC test could be a possible representation of the material deformation in DSIF

    Rare Kaon Decay K^+ --> \pi^+ \nu \bar{\nu} in SU(3)_C X SU(3)_L X U(1)_N Models

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    The rare kaon decay K^+ --> \pi^+ \nu \bar{\nu} is considered in the framework of the models based on the SU(3)_C X SU(3)_L X U(1)_N (3 - 3 - 1) gauge group. It is shown that a lower bound of the Z' mass in the 3 - 3 - 1 model with right-handed neutrinos at a value of 3 TeV is derived, while that in the minimal version -- 1.7 TeV.Comment: 7 pages, 1 figure, late
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