3,296 research outputs found

    Computation of the Modes of Elliptic Waveguides with a Curvilinear 2D Frequency-Domain Finite-Difference Approach

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    A scalar Frequency-Domain Finite-Difference approach to the mode computation of elliptic waveguides is presented. The use of an elliptic cylindrical grid allows us to take exactly into account the curved boundary of the structure and a single mesh has been used both for TE and TM modes. As a consequence, a high accuracy is obtained with a reduced computational burden, since the resulting matrix is highly sparse

    Geminal wavefunctions with Jastrow correlation: a first application to atoms

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    We introduce a simple generalization of the well known geminal wavefunction already applied in Quantum Chemistry to atoms and small molecules. The main feature of the proposed wavefunction is the presence of the antisymmetric geminal part together with a Jastrow factor. Both the geminal and the Jastrow play a crucial role in determining the remarkable accuracy of the many-body state: the former permits the correct treatment of the nondynamic correlation effects, the latter allows the wavefunction to fulfill the cusp conditions and makes the geminal expansion rapidly converging to the lowest possible variational energies. This ansatz is expected to provide a substantial part of the correlation energy for general complex atomic and molecular systems. The antisymmetric geminal term can be written as a single determinant even in the polarized cases. In general, therefore, the computational effort to sample this correlated wavefunction is not very demanding. We applied this Jastrow-geminal approach to atoms up to Z=15, always getting good variational energies, by particularly improving those with a strong multiconfigurational nature. Our wavefunction is very useful for Monte Carlo techniques, such as Fixed node. Indeed, the nodal surface obtained within this approach can be substantially improved through the geminal expansion.Comment: 14 pages, 2 figures, submitted to J. Chem. Phy

    Vector meson production in pp collisions at √s = 7TeV measured with the ALICE detector

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    Vector mesons are key probes of the hot and dense state of strongly interacting matter produced in heavy-ion collisions. Their dileptonic decay channel is particularly suitable for these studies, since dileptons have negligible final-state interactions in QCD matter. A measurement of the φ and ω differential cross sections was performed by the ALICE experiment in pp collisions at √s = 7TeV, through their decay in muon pairs, for pT > 1GeV/c and 2.5 < y < 4

    Vector meson production at √s = 7TeV and at √s = 2.76 TeV measured with the ALICE detector

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    Vector mesons are key probes of the hot and dense state of strongly interacting matter produced in heavy ion collisions. Their dilepton decay channel is particularly suitable for these studies, since dileptons have negligible final state interactions in QCD matter. We present the absolute production cross sections of φ and ω mesons measured with the ALICE muon spectrometer in the rapidity range 2.5 < y < 4 in pp collisions at √s = 7TeV and at √s = 2.76TeV, and the φ/(ρ+ω) ratio measured in Pb-Pb collisions at √sNN = 2.76TeV

    Electromagnetic analysis and performance comparison of fully 3D-printed antennas

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    In this work, the possibility of directly prototyping antennas by exploiting additive manufacturing 3D-printing technology is investigated. In particular, the availability of printable filaments with interesting conductive properties allows for printing of even the antenna conductive elements. Three samples of a 2.45 GHz microstrip patch antenna have been 3D-printed by using different approaches and materials, and their performance evaluated and compared. In particular, the same dielectric substrate printed in polylactic acid (PLA) has been adopted in all cases, whilst copper tape and two different conductive filaments have been used to realize the conductive parts of the three antenna samples, respectively. Even if an expected radiation efficiency reduction has been observed for the conductive filament case, the comparative analysis clearly demonstrates that 3D-printing technology can be exploited to design working fully-printed antennas, including the conductive parts

    UK Renal Registry 18th Annual Report: Chapter 3 Demographic and Biochemistry Profile of Kidney Transplant Recipients in the UK in 2014: National and Centre-specific Analyses.

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    There was a 2% fall in overall renal transplant numbers in 2014, with a significant fall in kidney donation from donors after circulatory death (10%). In 2014, death-censored renal transplant failure rates in prevalent patients were similar to previous years at 2.4% per annum. Transplant patient death rates remained stable at 2.3 per 100 patient years. The median age of incident and prevalent renal transplant patients in the UK was 50.6 and 53.3 years respectively. The median eGFR of prevalent renal transplant recipients was 52.5 ml/min/1.73 m2. The median eGFR of patients one year after transplantation was 57.4 ml/min/1.73 m2 post live transplant, 53.6 ml/min/1.73 m2 post brainstem death transplant and 50.1 ml/min/1.73 m2 post circulatory death transplant. In 2014, 13% of prevalent transplant patients had eGFR ,30 ml/min/1.73 m2. The median decline in eGFR slope beyond the first year after transplantation was −0.48 ml/min/1.73 m2/year.In 2014, malignancy (26%) and infection (24%) remained the commonest causes of death in patients with a functioning renal transplant

    Laser scanning the Garisenda and Asinelli towers in Bologna (Italy): detailed deformation patterns of two ancient leaning buildings

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    The Asinelli and Garisenda towers are the main symbol of the city of Bologna (Italy). These leaning towers, whose heights are about 97 m and 48 m respectively, were built during the early 12th century and are two of the few surviving ones from about a hundred tall medieval buildings that once characterized the city. Therefore, they are part of the Italian cultural heritage and their safeguard is extremely important. In order to evaluate in detail the deformations of these towers, in particular the deviations from a regular inclination of their walls, the terrestrial laser scanning (TLS) has been used and an efficient direct analysis method has been developed. The towers have been scanned from 6 viewpoints, providing 19 point clouds with a complete coverage of the visible surfaces with large overlap areas. For each tower, after the registration of the partial point clouds into a common reference frame, an accurate morphological analysis of the acquired surfaces has been carried out. The results show several zones affected by significant deformations and inclination changes. In the case of the Asinelli tower, for which a finite element model is available, the results have also been interpreted on the basis of the static load and normal modes. The correspondence between the measured deformation and the theoretically expected deformation, caused by a seismic sequence, is clear. This fact suggests a high sensibility of the tower to dynamic loads. Although a direct evaluation of the risk cannot be carried out with the obtained results, they lead to the general indication that the structural health of these buildings must be frequently checked and that man-made loads (e.g. vibration due to vehicular traffic) should be avoided or at least reduced

    The 3D-Printed Non-Radiating Edge Gap-Coupled Curved Patch Antenna

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    The use of parasitic resonant patches is a widespread technique to improve the bandwidth of microstrip patch antennas. Exploiting the free form-factor allowed by 3D-printing manufacturing technology, we present here a novel curved patch antenna layout, based on the non-radiating edge gap-coupled patch configuration. The proposed antenna is composed of a central curved patch, fed by a coaxial probe, and two gap-coupled parasitic side curved patches. This solution features a percentage impedance bandwidth of 16.3% using symmetrical parasitic side patches and 31.5% using asymmetrical side patches. A significant improvement of the bandwidth in comparison with both the standard non-radiating edge gap-coupled microstrip antenna (6.1% bandwidth) and the standard curved patch antenna (9% bandwidth) is achieved. Design and optimization of the proposed configuration are performed using the commercial software CST Studio Suite at the center frequency of 2.45 GHz. Prototypes of the symmetrical curved non-radiating edge gap-coupled patch antenna have been manufactured for the experimental verification, using a curved 3D-printed polylactic acid (PLA) substrate, fabricated with the commercial 3D printer PRUSA MK3S + and a 50 Ό m -thick adhesive aluminum tape for the metallization. Measured results show a very good agreement with simulations

    A Novel Design for Dual-Band Wearable Textile Eighth-Mode SIW Antennas

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    A novel wearable textile dual-band antenna configuration based on a substrate integrated waveguide (SIW) cavity is presented. The miniaturization of the antenna is achieved by exploiting the magnetic field symmetry of a square SIW cavity, reducing its size to 1/8 of the full square cavity with an eighth-mode SIW configuration. This solution is applied to the design of a wearable dual-band antenna for Long Range (LoRa) applications. The antenna operating frequency covers both the UHF LoRa bands, the European (863-870 MHz) and the North American (902-928 MHz). The proposed design provides a low-cost and compact antenna, which is easy to fabricate and ensures a very good isolation and robustness with respect to the human body proximity. The commercial software CST Studio Suite has been used for the antenna design and simulations. A prototype has been fabricated and the measured results are in good agreement with numerical simulations

    Le tecniche di indagine NDT nel processo di restauro e consolidamento di edifici soggetti a tutela

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    Le attivitĂ  di restauro e consolidamento di edifici soggetti a tutela sono fortemente ancorate alla conoscenza del bene, alla consistenza geometrico-strutturale e a quella materica, nonchĂ© all’analisi del degrado del manufatto e del suo stato di conservazione in tutti i suoi elementi. Altri aspetti tecnici da portare in conto sono ovviamente quelli legati al monitoraggio da attuare eventualmente in fase di diagnosi e obbligatoriamente in fase di esercizio, al fine di disporre di una robusta mole di dati per governare l’attivitĂ  manutentiva. Un valido supporto all’insieme di queste problematiche Ăš offerto oggi dalle tecniche non distruttive (NDT), le quali si inseriscono sia nel processo di screening conoscitivo del manufatto che nel processo di progettazione, di realizzazione degli interventi e di vita utile del bene. In questo contesto, la presente nota illustra una panoramica di alcune delle moderne tecniche di indagine NDT impiegate nelle attivitĂ  di rilievo, di valutazione dello stato dei materiali e nelle attivitĂ  di monitoraggio sia propedeutiche alla redazione del progetto, sia nel corso dell’esercizio. In riferimento a quest’ultimo aspetto, le tecniche illustrate mirano ad essere parte integrante di una metodologia di controllo "routinaria" da esercitare in continuo e con la possibilitĂ  di essere interrogabile anche in tempo reale. Alcuni esempi applicativi qui riportati, seppur in forma sintetica, consentiranno di apprezzare i benefici derivanti dall'utilizzo di tecniche NDT, il cui punto di forza risiede soprattutto nel loro essere non invasive e autodiagnosticanti
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