16,919 research outputs found

    Application Experiences of NASTRAN Thermal Analysis in Engineering

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    The application of the thermal analysis phase of NASTRAN in engineering is described. Some illustrative samples are presented to demonstrate the applicability and limitation of NASTRAN thermal analysis capability. The results of the evaluation of the relative efficiency, applicability and accuracy among NASTRAN, other finite element programs, and finite difference programs are also presented

    Determining the venting efficiency of simple chimneys for buoyant plumes

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    We present preliminary results from an examination of the capture and venting of a buoyant plume by a chimney. The aim is to enable improved management of indoor pollutant sources – for instance, the plume rising from a cooking pan in a kitchen or a cooking fire in a hut. Using the principle of dynamic similarity, we precise ly and controllably model the behaviour of indoor plumes by using saline solutions ejected into an enclosure containing freshwater. These well - established laboratory analogue techniques enable the location and concentration of tracer in the plume to be eas ily tracked, reflecting the evolution of pollutants carried in the plume. Focusing on a plume within a room containing a quiescent ambient environment, we identify two physical mechanisms potentially responsible for driving the removal of pollutants. The f irst, we describe as the capture of the plume, a process driven by the direct interaction between the plume and the evacuation opening; the second, we describe as the draining flow driven by a buoyant layer of fluid which may accumulate at the ceiling and is then evacuated through the effects of buoyancy. We first demonstrate that the addition of a simple cylindrical chimney that hangs downwards from an opening in the (analogue) ceiling increases the venting efficiency of these potentially polluting plumes. We go on to examine how the capture efficiency of these simple chimneys varies as the relative size of the plume and the chimney are altered, and demonstrate that simple model can provide predictions of the observed variation in capture efficiency

    N=3{\cal N}=3 Supersymmetric Effective Action of D2-branes in Massive IIA String Theory

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    We obtain a new-type of N=3{\cal N}=3 Yang-Mills Chern-Simons theory from the Mukhi-Papageorgakis Higgsing of the N=3{\cal N}=3 Gaiotto-Tomasiello theory. This theory has N=1{\cal N}=1 BPS fuzzy funnel solution which is expressed in terms of the seven generators of SU(3), excluding T8T_8. We propose that this is an effective theory of multiple D2-branes with D6- and D8-branes background in massive IIA string theory.Comment: 22 pages, positive definite form of potential is added, some comments are change

    The genetics of a putative social trait in natural populations of yeast

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    The sharing of secreted invertase by yeast cells is a well established laboratory model for cooperation, but the only evidence that such cooperation occurs in nature is that the SUC loci, which encode invertase, vary in number and functionality. Genotypes that do not produce invertase can act as “cheats” in laboratory experiments, growing on the glucose that is released when invertase producers, or “cooperators”, digest sucrose. However, genetic variation for invertase production might instead be explained by adaptation of different populations to different local availabilities of sucrose, the substrate for invertase. Here we find that, 110 wild yeast strains isolated from natural habitats, all contained a single SUC locus and produced invertase; none were “cheats”. The only genetic variants we found were three strains isolated instead from sucrose-rich nectar, which produced higher levels of invertase from three additional SUC loci at their sub-telomeres. We argue that the pattern of SUC gene variation is better explained by local adaptation than by social conflict

    Structure functions near the chiral limit

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    We compute hadron masses and the lowest moments of unpolarized and polarized nucleon structure functions down to pion masses of 300 MeV, in an effort to make unambiguous predictions at the physical light quark mass.Comment: 3 pages, 3 figures, Lattice2002(matrixel

    Quantum energy teleportation in a quantum Hall system

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    We propose an experimental method for a quantum protocol termed quantum energy teleportation (QET), which allows energy transportation to a remote location without physical carriers. Using a quantum Hall system as a realistic model, we discuss the physical significance of QET and estimate the order of energy gain using reasonable experimental parameters

    On predictability of rare events leveraging social media: a machine learning perspective

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    Information extracted from social media streams has been leveraged to forecast the outcome of a large number of real-world events, from political elections to stock market fluctuations. An increasing amount of studies demonstrates how the analysis of social media conversations provides cheap access to the wisdom of the crowd. However, extents and contexts in which such forecasting power can be effectively leveraged are still unverified at least in a systematic way. It is also unclear how social-media-based predictions compare to those based on alternative information sources. To address these issues, here we develop a machine learning framework that leverages social media streams to automatically identify and predict the outcomes of soccer matches. We focus in particular on matches in which at least one of the possible outcomes is deemed as highly unlikely by professional bookmakers. We argue that sport events offer a systematic approach for testing the predictive power of social media, and allow to compare such power against the rigorous baselines set by external sources. Despite such strict baselines, our framework yields above 8% marginal profit when used to inform simple betting strategies. The system is based on real-time sentiment analysis and exploits data collected immediately before the games, allowing for informed bets. We discuss the rationale behind our approach, describe the learning framework, its prediction performance and the return it provides as compared to a set of betting strategies. To test our framework we use both historical Twitter data from the 2014 FIFA World Cup games, and real-time Twitter data collected by monitoring the conversations about all soccer matches of four major European tournaments (FA Premier League, Serie A, La Liga, and Bundesliga), and the 2014 UEFA Champions League, during the period between Oct. 25th 2014 and Nov. 26th 2014.Comment: 10 pages, 10 tables, 8 figure

    Analisis Pengaruh Satisfaction, Trust Dan Commitment Terhadap Repurchase Intentions Pelanggan Tetap Hotel Raden Wijaya Mojokerto

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    Penelitian ini dilakukan untuk menganalisa pengaruh satisfaction, trust dan commitment pelanggan tetap terhadap repurchase intentions serta faktor yang berpengaruh paling dominan terhadap repurchase intentions di Hotel Raden Wijaya Mojokerto. Satisfaction dilihat dari segi fasilitas, price dan service. Trust dilihat dari reliability dan integrity. Commitment dilihat dari personal identification with organization, psychological attachment, concern for the repurchase welfare, dan willingness to be loyal. Repurchase intentions dilihat dari resistance against better alternatives, willingness to pay premium price, dan intention of word of mouth.Teknik analisa yang digunakan adalah statistik deskripstif dan regresi linier berganda. Berdasarkan penelitian terhadap 111 responden, hasil penelitian menunjukkan bahwa Satisfaction, Trust dan Commitment berpengaruh secara positif terhadap Repurchase Intention di Hotel Raden Wijaya Mojokerto. Trust menjadi faktor yang berpengaruh paling dominan terhadap Repurchase Intention di Hotel Raden Wijaya Mojokerto

    New selection rules for resonant Raman scattering on quantum wires

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    The bosonisation technique is used to calculate the resonant Raman spectrum of a quantum wire with two electronic sub-bands occupied. Close to resonance, the cross section at frequencies in the region of the inter sub-band transitions shows distinct peaks in parallel polarisation of the incident and scattered light that are signature of collective higher order spin density excitations. This is in striking contrast to the conventional selection rule for non-resonant Raman scattering according to which spin modes can appear only in perpendicular polarisation. We predict a new selection rule for the excitations observed near resonance, namely that, apart from charge density excitations, only spin modes with positive group velocities can appear as peaks in the spectra in parallel configuration close to resonance. The results are consistent with all of the presently available experimental data.Comment: 7 pages, 2 figure

    Quantum receiver beyond the standard quantum limit of coherent optical communication

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    The most efficient modern optical communication is known as coherent communication and its standard quantum limit (SQL) is almost reachable with current technology. Though it has been predicted for a long time that this SQL could be overcome via quantum mechanically optimized receivers, such a performance has not been experimentally realized so far. Here we demonstrate the first unconditional evidence surpassing the SQL of coherent optical communication. We implement a quantum receiver with a simple linear optics configuration and achieve more than 90% of the total detection efficiency of the system. Such an efficient quantum receiver will provide a new way of extending the distance of amplification-free channels, as well as of realizing quantum information protocols based on coherent states and the loophole-free test of quantum mechanics.Comment: 5 pages, 3 figure
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