20,016 research outputs found

    A fast 3-D object recognition algorithm for the vision system of a special-purpose dexterous manipulator

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    A fast 3-D object recognition algorithm that can be used as a quick-look subsystem to the vision system for the Special-Purpose Dexterous Manipulator (SPDM) is described. Global features that can be easily computed from range data are used to characterize the images of a viewer-centered model of an object. This algorithm will speed up the processing by eliminating the low level processing whenever possible. It may identify the object, reject a set of bad data in the early stage, or create a better environment for a more powerful algorithm to carry the work further

    Question of Peccei-Quinn symmetry and quark masses in the economical 3-3-1 model

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    We show that there is an infinite number of U(1) symmetries like Peccei-Quinn symmetry in the 3-3-1 model with minimal scalar sector---two scalar triplets. Moreover, all of them are completely broken due to the model's scalars by themselves (notice that these scalars as known have been often used to break the gauge symmetry and generating the masses for the model's particles). There is no any residual Peccei-Quinn symmetry. Because of the minimal scalar content there are some quarks that are massless at tree-level, but they can get consistent mass contributions at one-loop due to this fact. Interestingly, axions as associated with the mentioned U(1)s breaking (including Majoron due to lepton-charge breaking) are all gauged away because they are also the Goldstone bosons responsible for the gauge symmetry breaking as usual.Comment: 25 pages, 4 figures, revised version, to appear in Physical Review

    The A-decomposability of the Singer construction

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    Let RsMR_s M denote the Singer construction on an unstable module MM over the Steenrod algebra AA at the prime two; RsMR_s M is canonically a subobject of PsMP_s\otimes M, where PsP_s is the polynomial algebra on s generators of degree one. Passage to AA-indecomposables gives the natural transformation RsMFA(PsM)R_s M \rightarrow F \otimes_A (P_s \otimes M), which identifies with the dual of the composition of the Singer transfer and the Lannes-Zarati homomorphism. The main result of the paper proves the weak generalized algebraic spherical class conjecture, which was proposed by the first named author. Namely, this morphism is trivial on elements of positive degree when s>2. The condition s>2 is necessary, as exhibited by the spherical classes of Hopf invariant one and those of Kervaire invariant one.Comment: v2 15 pages. Minor revision. v3 17 pages, revision following referee's recommendations. Accepted for publication J. Al

    A probabilistic framework for tracking in wide-area environments

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    Surveillance in wide-area spatial environments is characterised by complex spatial layouts, large state space, and the use of multiple cameras/sensors. To solve this problem, there is a need for representing the dynamic and noisy data in the tracking tasks, and dealing with them at different levels of detail. This requirement is particularly suited to the Layered Dynamic Probabilistic Network (LDPN), a special type of Dynamic Probabilistic Network (DPN). In this paper, we propose the use of LDPN as the integrated framework for tracking in wide-area environments. We illustrate, with the help of a synthetic tracking scenario, how the parameters of the LDPN can be estimated from training data, and then used to draw predictions and answer queries about unseen tracks at various levels of detail.<br /

    Robust Dialog State Tracking for Large Ontologies

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    The Dialog State Tracking Challenge 4 (DSTC 4) differentiates itself from the previous three editions as follows: the number of slot-value pairs present in the ontology is much larger, no spoken language understanding output is given, and utterances are labeled at the subdialog level. This paper describes a novel dialog state tracking method designed to work robustly under these conditions, using elaborate string matching, coreference resolution tailored for dialogs and a few other improvements. The method can correctly identify many values that are not explicitly present in the utterance. On the final evaluation, our method came in first among 7 competing teams and 24 entries. The F1-score achieved by our method was 9 and 7 percentage points higher than that of the runner-up for the utterance-level evaluation and for the subdialog-level evaluation, respectively.Comment: Paper accepted at IWSDS 201

    Lepton flavor violating Higgs boson decays in seesaw models: new discussions

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    The lepton flavor violating decay of the Standard Model-like Higgs boson (LFVHD), h->\mu\tau, is discussed in seesaw models at the one-loop level. Based on particular analytic expressions of Passarino-Veltman functions, the two unitary and 't Hooft Feynman gauges are used to compute the branching ratio of LFVHD and compare with results reported recently. In the minimal seesaw (MSS) model, the branching ratio was investigated in the whole valid range 10^{-9}-10^{15} GeV of new neutrino mass scale m_{n_6}. Using the Casas-Ibarra parameterization, this branching ratio enhances with large and increasing m_{n_6}. But the maximal value can reach only order of 10^{-11}. Interesting relations of LFVHD predicted by the MSS and inverse seesaw (ISS) model are discussed. The ratio between two LFVHD branching ratios predicted by the ISS and MSS is simply m^2_{n_6}\mu^{-2}_X, where \mu_X is the small neutrino mass scale in the ISS. The consistence between different calculations is shown precisely from analytical approach.Comment: 4 figures, 26 pages, some analytic formulas and statements are corrected. Main results are unchanged. New references added. Version published in NP

    Governance of built-heritage in a restrictive political system: The involvement of non-governmental stakeholders

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    Built-heritage conservation has increasingly become Hong Kong people's urgent concern since the years leading up to the territory's change of sovereignty from Great Britain to China, under political rules in which development takes priority over conservation. Built-heritage is a symbol of cultural identity and thus Hong Kong people's awareness of the importance of preserving them (Henderson, 2008). NGOs' sense of urgency in getting involved in built-heritage conservation also stems from operating within a political system which Scott (2010) describes as having a restrictive policy-making process, lacking in responsiveness to public demands and expectations. NGOs have three basic functions, namely, service provision, advocacy, and monitoring. Two case studies are used to illustrate these functions. The findings indicate that NGOs are most intensely involved in advocacy. NGOs involved in service provision have been selected through tightly-controlled processes. NGOs' monitoring activities were very limited. I argue that NGOs' role in built-heritage conservation is limited due to the restrictive political system. However, NGOs demonstrated insistent and resilient opposition to any top-down approach to decision-making, a sign that leads to the belief that despite of and because of the nature of the political system, NGOs' involvement in built-heritage is not only likely to intensify but also expand with government increasing the openness of the policy process to contain public pressure.postprin
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