10,023 research outputs found

    Cryptanalysis of a novel cryptosystem based on chaotic oscillators and feedback inversion

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    An analysis of a recently proposed cryptosystem based on chaotic oscillators and feedback inversion is presented. It is shown how the cryptosystem can be broken when Duffing's oscillator is considered. Some implementation problems of the system are also discussed.Comment: 9 pages, 3 figures, latex forma

    Z-dependent Barriers in Multifragmentation from Poissonian Reducibility and Thermal Scaling

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    We explore the natural limit of binomial reducibility in nuclear multifragmentation by constructing excitation functions for intermediate mass fragments (IMF) of a given element Z. The resulting multiplicity distributions for each window of transverse energy are Poissonian. Thermal scaling is observed in the linear Arrhenius plots made from the average multiplicity of each element. ``Emission barriers'' are extracted from the slopes of the Arrhenius plots and their possible origin is discussed.Comment: 15 pages including 4 .ps figures. Submitted to Phys. Rev. Letters. Also available at http://csa5.lbl.gov/moretto

    Space and Time pattern of mid-velocity IMF emission in peripheral heavy-ion collisions at Fermi energies

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    The emission pattern in the V_perp - V_par plane of Intermediate Mass Fragments with Z=3-7 (IMF) has been studied in the collision 116Sn + 93Nb at 29.5 AMeV as a function of the Total Kinetic Energy Loss of the reaction. This pattern shows that for peripheral reactions most of IMF's are emitted at mid-velocity. Coulomb trajectory calculations demonstrate that these IMF's are produced in the early stages of the reaction and shed light on geometrical details of these emissions, suggesting that the IMF's originate both from the neck and the surface of the interacting nuclei.Comment: 4 pages, 3 figures, RevTex 3.1, submitted to Phys. Rev. Letter

    Partner selection in green supply chains using PSO – a practical approach

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    Partner selection is crucial to green supply chain management as the focal firm is responsible for the environmental performance of the whole supply chain. The construction of appropriate selection criteria is an essential, but often neglected pre-requisite in the partner selection process. This paper proposes a three-stage model that combines Dempster-Shafer belief acceptability theory and particle swarm optimization technique for the first time in this application. This enables optimization of both effectiveness, in its consideration of the inter-dependence of a broad range of quantitative and qualitative selection criteria, and efficiency in its use of scarce resources during the criteria construction process to be achieved simultaneously. This also enables both operational and strategic attributes can be selected at different levels of hierarchy criteria in different decision-making environments. The practical efficacy of the model is demonstrated by an application in Company ABC, a large Chinese electronic equipment and instrument manufacturer

    Anatomy of the “false thumb” of Tremarctos ornatus (Carnivora, Ursidae, Tremarctinae) : phylogenetic and functional implications

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    Se describe por primera vez el sesamoideo radial o “falso pulgar” del oso de anteojos (Tremarctos ornatus), mostrando la gran similitud morfológica con el del panda gigante (Ailuropoda melanoleuca) y las diferencias que presenta con el resto de los Ursidae. Esto apunta a la existencia de un origen común para esta estructura en ambas especies, pero considerando las filogenias aceptadas de Ursidae, la presencia de falso pulgar en T. ornatus y A. melanoleuca sería una simplesiomorfía respecto al resto de úrsidos, en los cuales el sesamoideo radial nunca aumentó de tamaño, careciendo de la especializada función que posee en Tremarctinae y Ailuropodinae.We describe for the first time the radial sesamoid or “false thumb” of the spectacled bear (Tremarctos ornatus), showing its great morphological similarities with that of the giant panda (Ailuropoda melanoleuca) and the differences with that of the rest of the Ursidae. This points to the existence of a common origin for this structure in both species, but considering the accepted phylogenies of ursids, the sharing of a “false thumb” in T. ornatus and A. melanoleuca would be a plesiomorphy for these groups, whereas in the rest of the ursids the radial sesamoid was probably reduced, lacking the specialised function that this bone has in Tremarctinae and [email protected] [email protected]

    Avaliação da biomassa e carbono do sistema agroflorestal da bracatinga.

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    Organizado por Patricia Póvoa de Mattos, Celso Garcia Auer, Rejane Stumpf Sberze, Katia Regina Pichelli e Paulo César Botosso

    Aerostructural Optimization of Long Span Bridges: Current Advances and Challenges

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    Structures Congress 2020. 5-8 abril, 2020. St. Louis, Missouri[Abstract] This paper describes the evolution of deck shape of long span bridges since the Tacoma Narrows collapse trying to avoid undesirable aerodynamic behavior under wind flow and the trend in the last decades to increase the length of the main span of suspension and cable stayed bridges. The necessity to use advanced technologies to help the engineer to obtain the best possible design is highlighted and the advantages of applying optimization methodologies is encouraged. It is explained that this approach requires to use only numerical tools and hence to eliminate experimental studies, as wind tunnel tests using reduced models of full bridge of a segment of the deck, and their substitution by computational fluid dynamics (CFD) simulations. After doing so, the current capabilities of this approach are presented and, finally, the problems that need to be solved to have a fully operational methodology able to be implemented in real structures are outlined.This research has been funded by the Spanish Ministry of Economy and Competitiveness in the frame of the research project BIA2016-76656-R and the Galician regional government (including FEDER Funding) reference ED431C 2017/72. M. Cid Montoya has been funded by the Galician regional government (Xunta de Galicia) with reference ED481B 2018/053 and the Fulbright postdoctoral scholarship programXunta de Galicia; ED431C 2017/72Xunta de Galicia; ED481B 2018/05

    No Drama: Key Elements to the Success of an HIV/STI-Prevention Mass-Media Campaign

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    We qualitatively examined gay men’s reactions to the national “Drama Downunder” HIV/STI social marketing campaign targeting gay men in Australia to identify key campaign elements that underpinned the demonstrated effectiveness of the campaign. We present findings from six qualitative focus groups held with 49 participants as part of the evaluation of the sexual-health-promotion campaign over 2008–2009. Participants identified attention-grabbing images, a humorous approach, positive and simple tailored messaging, and the use of mainstream media as campaign features crucial in normalizing sexual health testing, driving campaign engagement, and ensuring high message exposure. Our results suggest that designers of future campaigns should strive to balance positive and negative campaign images and messages, and find new ways to engage men with sexual health topics, particularly younger gay men. We discuss the implications of our findings about campaign effectiveness for future health-promotion campaigns and message design
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