6,699 research outputs found

    Nucleon-nucleon resonances at intermediate energies using a complex energy formalism

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    We apply our method of complex scaling, valid for a general class of potentials, in a search for nucleon-nucleon S-matrix poles up to 2 GeV laboratory kinetic energy. We find that the realistic potentials JISP16, constructed from inverse scattering, and chiral field theory potentials N3^3LO and N2^2LOopt_{opt} support resonances in energy regions well above their fit regions. In some cases these resonances have widths that are narrow when compared with the real part of the S-matrix pole.Comment: 7 pages, 5 figures, 2 Table

    System Identification of Constructed Facilities: Challenges and Opportunities Across Hazards

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    The motivation, success and prevalence of full-scale monitoring of constructed buildings vary considerably across the hazard of concern (earthquakes, strong winds, etc.), due in part to various fiscal and life safety motivators. Yet while the challenges of successful deployment and operation of large-scale monitoring initiatives are significant, they are perhaps dwarfed by the challenges of data management, interrogation and ultimately system identification. Practical constraints on everything from sensor density to the availability of measured input has driven the development of a wide array of system identification and damage detection techniques, which in many cases become hazard-specific. In this study, the authors share their experiences in fullscale monitoring of buildings across hazards and the associated challenges of system identification. The study will conclude with a brief agenda for next generation research in the area of system identification of constructed facilities

    An Innovative Approach to Achieve Compositionality Efficiently using Multi-Version Object Based Transactional Systems

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    In the modern era of multicore processors, utilizing cores is a tedious job. Synchronization and communication among processors involve high cost. Software transaction memory systems (STMs) addresses this issues and provide better concurrency in which programmer need not have to worry about consistency issues. Another advantage of STMs is that they facilitate compositionality of concurrent programs with great ease. Different concurrent operations that need to be composed to form a single atomic unit is achieved by encapsulating them in a single transaction. In this paper, we introduce a new STM system as multi-version object based STM (MVOSTM) which is the combination of both of these ideas for harnessing greater concurrency in STMs. As the name suggests MVOSTM, works on a higher level and maintains multiple versions corresponding to each key. We have developed MVOSTM with the unlimited number of versions corresponding to each key. In addition to that, we have developed garbage collection for MVOSTM (MVOSTM-GC) to delete unwanted versions corresponding to the keys to reduce traversal overhead. MVOSTM provides greater concurrency while reducing the number of aborts and it ensures compositionality by making the transactions atomic. Here, we have used MVOSTM for the list and hash-table data structure as list-MVOSTM and HT- MVOSTM. Experimental results of list-MVOSTM outperform almost two to twenty fold speedup than existing state-of-the-art list based STMs (Trans-list, Boosting-list, NOrec-list, list-MVTO, and list-OSTM). HT-MVOSTM shows a significant performance gain of almost two to nineteen times better than existing state-of-the-art hash-table based STMs (ESTM, RWSTMs, HT-MVTO, and HT-OSTM). MVOSTM with list and hash-table shows the least number of aborts among all the existing STM algorithms. MVOSTM satisfies correctness-criteria as opacity.Comment: 35 pages, 23 figure

    First-order transition in small-world networks

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    The small-world transition is a first-order transition at zero density pp of shortcuts, whereby the normalized shortest-path distance undergoes a discontinuity in the thermodynamic limit. On finite systems the apparent transition is shifted by ΔpLd\Delta p \sim L^{-d}. Equivalently a ``persistence size'' Lp1/dL^* \sim p^{-1/d} can be defined in connection with finite-size effects. Assuming LpτL^* \sim p^{-\tau}, simple rescaling arguments imply that τ=1/d\tau=1/d. We confirm this result by extensive numerical simulation in one to four dimensions, and argue that τ=1/d\tau=1/d implies that this transition is first-order.Comment: 4 pages, 3 figures, To appear in Europhysics Letter

    LOCAL EARTHQUAKE TOMOGRAPHY IN THE BROADER AREA OF WESTERN CORINTH GULF

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    Η παρούσα εργασία περιγράφει τα αποτελέσματα της τρισδιάστατης τομογραφίας που πραγματοποιήθηκε στην ευρύτερη περιοχή του Δυτικού Κορινθιακού Κόλπου με σκοπό την χαρτογράφηση ενεργών τεκτονικών δομών. Για την πραγματοποίηση της παρούσης μελέτης χρησιμοποιήθηκαν δεδομένα από περισσότερους των 2,000 σεισμών οι οποίοι καταγράφηκαν από το Ενιαίο Σεισμολογικό Δίκτυο και το αντίστοιχο του Εργαστηρίου της Κορινθιακής Τάφρου (CRLN).Με την τομογραφική αντιστροφή παράγουμε και πραγματοποιούμε την ερμηνεία τρισδιάστατων μοντέλων κυμάτων χώρου (Vp, Vs) και του αντίστοιχου λόγου τους (Vp/Vs) για την περιοχή μελέτης. Τα τελικά αποτελέσματα καταδεικνύουν ορισμένες ενδιαφέρουσες δομές, κυρίως όσον αφορά τον λόγο Vp/Vs,που συσχετίζουν την κατανομή των προσδιορισθέντων υποκέντρων με διαφοροποιήσεις στη λιθολογία ή στο περιεχόμενο των γεωλογικών σχηματισμών σε ρευστά. Στην περιοχή του Πατραϊκού, ένας ανερχόμενος δόμος υψηλής ταχύτητας εντοπίστηκε, ο οποίος κάλλιστα μπορεί να συνδεθεί με την τεκτονική αλατούχων δόμων στο Αλπικό υπόβαθρο, γεγονός που επηρεάζει την κυκλοφορία των ρευστών καθώς και τη δράση των τοπικών ρηγμάτων.In this study, we applied Local Earthquake Tomography in order to investigate the detailed 3-D structure within and around the broader region of Western Corinth Gulf which is one of the most seismically active regions in the world. We use data from the 2012-2014 time-period, selecting about 2,000 seismic events recorded by the local seismic stations of Hellenic Unified Seismological Network (HUSN) and the Corinth Rift Laboratory Network (CRLN). Applying Tomographic Inversion, we produce and interpret 3-D models of Vp, Vs and Vp/Vs ratio in the study area. The obtained results shows several distinct structures, namely areas of high and low Vp/Vs ratio correlating the hypocenter distribution with changes in lithology or fluid concentration. In the area of Patraikos Gulf, an ascending velocity volume was traced that could possibly be connected to salt tectonics in the alpine basement, effecting the fluid circulation as well as the behavior of local faults

    Holographic Renormalization of general dilaton-axion gravity

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    We consider a very general dilaton-axion system coupled to Einstein-Hilbert gravity in arbitrary dimension and we carry out holographic renormalization for any dimension up to and including five dimensions. This is achieved by developing a new systematic algorithm for iteratively solving the radial Hamilton-Jacobi equation in a derivative expansion. The boundary term derived is valid not only for asymptotically AdS backgrounds, but also for more general asymptotics, including non-conformal branes and Improved Holographic QCD. In the second half of the paper, we apply the general result to Improved Holographic QCD with arbitrary dilaton potential. In particular, we derive the generalized Fefferman-Graham asymptotic expansions and provide a proof of the holographic Ward identities.Comment: 42 pages. v2: two references added. Version published in JHEP. v3: fixed minor typos in eqs. (1.6), (2.3), (3.20), (A.3), (B.8), (B.12) and (B.22

    "Community Development Banking, A Proposal to Establish a Nationwide System of Community Development Banks"

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    This brief proposes that the establishment of a nationwide system of community development banks (CDBs) would advance the capital development of the economy. The proposal is based on the notion that a critical function of the financial system is not being adequately performed by existing institutions for low-income citizens, inner-city minorities, and entrepreneurs who seek modest financing for small businesses. The primary goals of the CDBs are to deliver credit, payment, and savings opportunities to communities not well served by banks and to provide financing throughout a designated area for businesses too small to attract the interest of the investment banking and normal commercial banking communities.

    The impact of Ti and temperature on the stability of Nb5Si3 phases: a first-principles study

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    Nb-silicide based alloys could be used at T > 1423 K in future aero-engines. Titanium is an important additive to these new alloys where it improves oxidation, fracture toughness and reduces density. The microstructures of the new alloys consist of an Nb solid solution, and silicides and other intermetallics can be present. Three Nb5Si3 polymorphs are known, namely αNb5Si3 (tI32 Cr5B3-type, D8l), βNb5Si3 (tI32 W5Si3-type, D8m) and γNb5Si3 (hP16 Mn5Si3-type, D88). In these 5–3 silicides Nb atoms can be substituted by Ti atoms. The type of stable Nb5Si3 depends on temperature and concentration of Ti addition and is important for the stability and properties of the alloys. The effect of increasing concentration of Ti on the transition temperature between the polymorphs has not been studied. In this work first-principles calculations were used to predict the stability and physical properties of the various Nb5Si3 silicides alloyed with Ti. Temperature-dependent enthalpies of formation were computed, and the transition temperature between the low (α) and high (β) temperature polymorphs of Nb5Si3 was found to decrease significantly with increasing Ti content. The γNb5Si3 was found to be stable only at high Ti concentrations, above approximately 50 at. % Ti. Calculation of physical properties and the Cauchy pressures, Pugh’s index of ductility and Poisson ratio showed that as the Ti content increased, the bulk moduli of all silicides decreased, while the shear and elastic moduli and the Debye temperature increased for the αNb5Si3 and γNb5Si3 and decreased for βNb5Si3. With the addition of Ti the αNb5Si3 and γNb5Si3 became less ductile, whereas the βNb5Si3 became more ductile. When Ti was added in the αNb5Si3 and βNb5Si3 the linear thermal expansion coefficients of the silicides decreased, but the anisotropy of coefficient of thermal expansion did not change significantly
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