4,922 research outputs found

    A framework for integrating syntax, semantics and pragmatics for computer-aided professional practice: With application of costing in construction industry

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    Producing a bill of quantity is a knowledge-based, dynamic and collaborative process, and evolves with variances and current evidence. However, within the context of information system practice in BIM, knowledge of cost estimation has not been represented, nor has it been integrated into the processes based on BIM. This paper intends to establish an innovative means of taking data from the BIM linked to a project, and using it to create the necessary items for a bill of quantity that will enable cost estimation to be undertaken for the project. Our framework is founded upon the belief that three components are necessary to gain a full awareness of the domain which is being computerised; the information type which is to be assessed for compatibility (syntax), the definition for the pricing domain (semantics), and the precise implementation environment for the standards being taken into account (pragmatics). In order to achieve this, a prototype is created that allows a cost item for the bill of quantity to be spontaneously generated, by means of the semantic web ontology and a forward chain algorithm. Within this paper, ‘cost items’ signify the elements included in a bill of quantity, including details of their description, quantity and price. As a means of authenticating the process being developed, the authors of this work effectively implemented it in the production of cost items. In addition, the items created were contrasted with those produced by specialists. For this reason, this innovative framework introduces the possibility of a new means of applying semantic web ontology and forward chain algorithm to construction professional practice resulting in automatic cost estimation. These key outcomes demonstrate that, decoupling the professional practice into three key components of syntax, semantics and pragmatics can provide tangible benefits to domain use

    The gauge algebra of double field theory and Courant brackets

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    We investigate the symmetry algebra of the recently proposed field theory on a doubled torus that describes closed string modes on a torus with both momentum and winding. The gauge parameters are constrained fields on the doubled space and transform as vectors under T-duality. The gauge algebra defines a T-duality covariant bracket. For the case in which the parameters and fields are T-dual to ones that have momentum but no winding, we find the gauge transformations to all orders and show that the gauge algebra reduces to one obtained by Siegel. We show that the bracket for such restricted parameters is the Courant bracket. We explain how these algebras are realised as symmetries despite the failure of the Jacobi identity.Comment: 25 pages, LaTe

    Automatic summarization of rushes video using bipartite graphs

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    In this paper we present a new approach for automatic summarization of rushes video. Our approach is composed of three main steps. First, based on a temporal segmentation, we filter sub-shots with low information content not likely to be useful in a summary. Second, a method using maximal matching in a bipartite graph is adapted to measure similarity between the remaining shots and to minimize inter-shot redundancy by removing repetitive retake shots common in rushes content. Finally, the presence of faces and the motion intensity are characterised in each sub-shot. A measure of how representative the sub-shot is in the context of the overall video is then proposed. Video summaries composed of keyframe slideshows are then generated. In order to evaluate the effectiveness of this approach we re-run the evaluation carried out by the TREC, using the same dataset and evaluation metrics used in the TRECVID video summarization task in 2007 but with our own assessors. Results show that our approach leads to a significant improvement in terms of the fraction of the TRECVID summary ground truth included and is competitive with other approaches in TRECVID 2007

    Consistent reductions of IIB*/M* theory and de Sitter supergravity

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    We construct consistent non-linear Kaluza Klein reduction ansatze for a subset of fields arising from the reduction of IIB* and M* theory on dS_5 x H^5 and dS_4 x AdS_7, respectively. These reductions yield four and five-dimensional de Sitter supergravities, albeit with wrong sign kinetic terms. We also demonstrate that the ansatze may be used to lift multi-centered de Sitter black hole solutions to ten and eleven dimensions. The lifted dS_5 black holes correspond to rotating E4-branes of IIB* theory.Comment: 27 pages, late

    SBV Regularity for Genuinely Nonlinear, Strictly Hyperbolic Systems of Conservation Laws in one space dimension

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    We prove that if tu(t)BV(R)t \mapsto u(t) \in \mathrm {BV}(\R) is the entropy solution to a N×NN \times N strictly hyperbolic system of conservation laws with genuinely nonlinear characteristic fields ut+f(u)x=0, u_t + f(u)_x = 0, then up to a countable set of times {tn}nN\{t_n\}_{n \in \mathbb N} the function u(t)u(t) is in SBV\mathrm {SBV}, i.e. its distributional derivative uxu_x is a measure with no Cantorian part. The proof is based on the decomposition of ux(t)u_x(t) into waves belonging to the characteristic families u(t)=i=1Nvi(t)r~i(t),vi(t)M(R), r~i(t)RN, u(t) = \sum_{i=1}^N v_i(t) \tilde r_i(t), \quad v_i(t) \in \mathcal M(\R), \ \tilde r_i(t) \in \mathrm R^N, and the balance of the continuous/jump part of the measures viv_i in regions bounded by characteristics. To this aim, a new interaction measure \mu_{i,\jump} is introduced, controlling the creation of atoms in the measure vi(t)v_i(t). The main argument of the proof is that for all tt where the Cantorian part of viv_i is not 0, either the Glimm functional has a downward jump, or there is a cancellation of waves or the measure μi,jump\mu_{i,\mathrm{jump}} is positive

    Microwave burst with fine spectral structures in a solar flare on 2011 August 9

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    On August 9, 2011, there was an X6.9 flare event occurred near the west limb of solar disk. From the observation obtained by the spectrometer of the Chinese Solar Broadband Radio Spectrometer in Huairou (SBRS/Huairou) around the flare, we find that this powerful flare has only a short-duration microwave burst of about only 5 minutes, and during the short-duration microwave burst, there are several kinds of fine structures on the spectrogram. These fine structures include very short-period pulsations, millisecond spike bursts, and type III bursts. The most interesting is that almost all of the pulses of very short-period pulsation (VSP) are structured by clusters of millisecond timescales of spike bursts or type III bursts. And there exists three different kinds of frequency drift rates in the VSP: the frequency drift rates with absolute value of about 55 - 130 MHz s^{-1} in the pulse groups, the frequency drift rates with absolute value of about 2.91 - 16.9 GHz s^{-1} on each individual pulse, and the frequency drift rates with absolute value of about 15 - 25 GHz s1^{-1}) at each individual spike burst or type III burst.Comment: 5 pages, 3 figure

    On supergravity solutions of space-like Dp-branes

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    Recently the time dependent solutions of type II supergravities in d=10d = 10, with the metric having the symmetry ISO(p+1)×SO(8p,1)ISO(p+1) \times SO(8-p, 1) have been given by two groups (Chen-Gal'tsov-Gutperle (CGG), [hep-th/0204071] and Kruczenski-Myers-Peet (KMP), [hep-th/0204144]). The supergravity solutions correspond to space-like Dpp-branes in type II string theory. While the CGG solution is a four parameter solution, the KMP solution is a three parameter solution and so in general they are different. This difference can be attributed to the fact that unlike the CGG solution, KMP uses a specific boundary condition for the metric and the dilaton field. It is shown that when we impose the boundary conditions used in the KMP solution to the CGG solution then both become three parameter solutions and they map to each other under a coordinate transformation along with a Hodge duality of the field strength. We also give the relations between the parameters characterizing the two solutions.Comment: 14 pages, LaTeX, v2: minor corrections and a reference adde

    Proteomic analysis of the rat ovary following chronic low-dose exposure to 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD)

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    2,3,7,8-Tetrachlorodibenzo-p-dioxin (TCDD) is a ubiquitously distributed endocrine-disrupting chemical and reproductive toxicant. In order to elucidate low-dose TCDD-mediated effects on reproductive or endocrine functions, female Sprague-Dawley rats were orally administered various concentrations (20, 50, or 125 ng/kg once weekly) TCDD for 29 wk. A proteomic analysis of the ovaries by two-dimensional gel electrophoresis and matrix-assisted laser desorption/ionization (MALDI) tandem mass spectrometry showed distinct changes in the levels of several proteins that are relevant markers of TCDD toxicity. Serum estradiol (E2) levels of TCDD-treated animals were markedly lower than control. There were no significant differences in bone mineral density (BMD) of femurs. The body weight of the 125-ng/kg TCDD group was significantly decreased relative to control and there was also a significant reduction in absolute and relative ovarian weights. Expressions of selenium binding protein 2, glutathione S-transferase mu type 3, Lrpap1 protein, NADPH, and peptidylprolyl isomerase D were upregulated, while prohibitin and N-ethylmaleimide-sensitive factor expression levels were downregulated. Data provide further insight into the mechanisms by which TCDD disrupts ovarian function by indicating which differential protein expressions following low-dose TCDD exposure

    Critical points of Wang-Yau quasi-local energy

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    In this paper, we prove the following theorem regarding the Wang-Yau quasi-local energy of a spacelike two-surface in a spacetime: Let Σ\Sigma be a boundary component of some compact, time-symmetric, spacelike hypersurface Ω\Omega in a time-oriented spacetime NN satisfying the dominant energy condition. Suppose the induced metric on Σ\Sigma has positive Gaussian curvature and all boundary components of Ω\Omega have positive mean curvature. Suppose HH0H \le H_0 where HH is the mean curvature of Σ\Sigma in Ω\Omega and H0H_0 is the mean curvature of Σ\Sigma when isometrically embedded in R3R^3. If Ω\Omega is not isometric to a domain in R3R^3, then 1. the Brown-York mass of Σ\Sigma in Ω\Omega is a strict local minimum of the Wang-Yau quasi-local energy of Σ\Sigma, 2. on a small perturbation Σ~\tilde{\Sigma} of Σ\Sigma in NN, there exists a critical point of the Wang-Yau quasi-local energy of Σ~\tilde{\Sigma}.Comment: substantially revised, main theorem replaced, Section 3 adde

    Eta absorption by mesons

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    Using the [SU(3)L×SU(3)R]global×[SU(3)V]local[SU(3)_{\mathrm{L}} \times SU(3)_{\mathrm{R}}]_{\mathrm{global}% }\times [SU(3)_V]_{\mathrm{local}} chiral Lagrangian with hidden local symmetry, we evaluate the cross sections for the absorption of eta meson (η% \eta) by pion (π\pi), rho (ρ\rho), omega (ω\omega), kaon (KK), and kaon star (KK^*) in the tree-level approximation. With empirical masses and coupling constants as well as reasonable values for the cutoff parameter in the form factors at interaction vertices, we find that most cross sections are less than 1 mb, except the reactions ρηKKˉ(KˉK)\rho\eta\to K\bar K^*(\bar KK^*), ωηKKˉ(KˉK)\omega\eta\to K\bar K^*(\bar KK^*), KηρKK^*\eta\to\rho K, and KηωKK^*\eta\to\omega K, which are a few mb, and the reactions πηKKˉ\pi\eta\to K\bar K and KηπKK\eta\to\pi K, which are more than 10 mb. Including these reactions in a kinetic model based on a schematic hydrodynamic description of relativistic heavy ion collisions, we find that the abundance of eta mesons likely reaches chemical equilibrium with other hadrons in nuclear collisions at the Relativistic Heavy Ion Collider.Comment: 29 pages, 10 figures, version to appear in Nucl. Phys.
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