7,377 research outputs found

    EOS: A project to investigate the design and construction of real-time distributed embedded operating systems

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    The EOS project is investigating the design and construction of a family of real-time distributed embedded operating systems for reliable, distributed aerospace applications. Using the real-time programming techniques developed in co-operation with NASA in earlier research, the project staff is building a kernel for a multiple processor networked system. The first six months of the grant included a study of scheduling in an object-oriented system, the design philosophy of the kernel, and the architectural overview of the operating system. In this report, the operating system and kernel concepts are described. An environment for the experiments has been built and several of the key concepts of the system have been prototyped. The kernel and operating system is intended to support future experimental studies in multiprocessing, load-balancing, routing, software fault-tolerance, distributed data base design, and real-time processing

    The Influence of Poly(Acrylic Acid) Molar Mass on the Properties of Polyalkenoate Cements Formed from Zinc Oxide/apatite Mixtures

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    The influence of poly (acrylic acid) molar mass was investigated on cements formed from zinc oxide-apatite mixtures at three aging times: one, seven and 28 days. Cements based on both hydroxyapatite and fluorapatite were investigated. The compressive strength, un-notched fracture strength and fracture toughness increased markedly with poly (acrylic acid) molar mass. The fracture toughness and un-notched fracture strength increased with aging time for the two highest molar mass cements but decreased with time for the two lowest molar mass cements. The greater chain entanglement density present in the higher molar mass cements is thought to contribute significantly to the cement stability in addition to the crosslinking of the polyacrylate chains by calcium and zinc ions. Substitution of hydroxyapatite by fluorapatite had no significant influence on the mechanical properties of the cements at aging times longer than one day

    An automatic system for modeling and controlling color quality of dyed leathers in tanneries

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    This paper presents an automatic system for modeling and controlling color quality of dyed leathers of an Italian tannery. The proposed software is implemented within the IT company system, and is fully integrated with the machineries of the finishing line, that is, a spraying cabin with a robotic carousel, and an electronic tintometer system. Suitable experimental tests according to the Design of Experiments (DoE) are firstly defined, executed and analyzed for a series of color tones of interest. In order to derive and validate a set of colorimetric models able to evaluate and predict the color rendering of painted leathers, a set of recipes of basic dye pigments and data of light reflection measured by a multispectral camera are used. Principal Component Analysis is applied for dimensionality reduction, and linear least squares regression is employed to identify these data-driven models, which are then used for color control purpose. A color correction feedback strategy is indeed developed in order to converge towards the various target formulations. The control algorithm aims at reaching the multispectral reading values of the reference, that is, the first sample of unknown color recipe starting from the most similar archive base and appropriately updating the recipe of pigments, by using the measurement of leather samples prepared from time to time by the finishing line machineries. A set of company data are used to successfully validate the identified colorimetric models and the proposed color correction strategy

    Galactic Center Radio Constraints on Gamma-Ray Lines from Dark Matter Annihilation

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    Recent evidence for one or more gamma-ray lines at ~ 130 GeV in the Fermi-LAT data from the Galactic Center has been interpreted as a hint for dark matter annihilation to Z{\gamma} or H{\gamma} with an annihilation cross section, ~ 10^{-27} cm^3 s^{-1} . We test this hypothesis by comparing synchrotron fluxes due to the electrons and positrons from the decay of the Z or the H boson only in the Galactic Center against radio data from the same region in the Galactic Center. We find that the radio data from single dish telescopes marginally constrain this interpretation of the claimed gamma lines for a contracted NFW profile. Already-operational radio telescopes such as LWA, VLA-Low and LOFAR, and future radio telescopes like SKA, which are sensitive to annihilation cross sections as small as 10^{-28} cm^3 s^{-1}, can confirm or rule out this scenario very soon. We discuss the assumptions on the dark matter profile, magnetic fields, and background radiation density profiles, and show that the constraints are relatively robust for any reasonable assumptions. Independent of the above said recent developments, we emphasize that our radio constraints apply to all models where dark matter annihilates to Z{\gamma} or H{\gamma}.Comment: v3: 18 pages, 7 figures. Minor changes. Published in Phys. Rev.

    Is attending a mental process?

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    The nature of attention has been the topic of a lively research programme in psychology for over a century. But there is widespread agreement that none of the theories on offer manage to fully capture the nature of attention. Recently, philosophers have become interested in the debate again after a prolonged period of neglect. This paper contributes to the project of explaining the nature of attention. It starts off by critically examining Christopher Mole’s prominent “adverbial” account of attention, which traces the failure of extant psychological theories to their assumption that attending is a kind of process. It then defends an alternative, process-based view of the metaphysics of attention, on which attention is understood as an activity and not, as psychologists seem to implicitly assume, an accomplishment. The entrenched distinction between accomplishments and activities is shown to shed new light on the metaphysics of attention. It also provides a novel diagnosis of the empirical state of play

    Investigating the veracity of self-reported post-traumatic growth: a profile analysis approach

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    Research into posttraumatic growth—positive psychological change that people report in their relationships, priorities in life, and self-perception after experiences of adversity—has been severely critiqued. We investigated the degree to which community members’ friends and relatives corroborated targets’ self-perceived positive and negative changes as measured by the Posttraumatic Growth Inventory-42. We found corroboration only for negative changes when we examined overall (averaged) scores. However, using a profile analysis procedure, we found significant participant–informant agreement on the domains of change that had relatively higher scores in the target’s profile and those that had relatively lower scores. Our results demonstrate that informants were able to observe that targets had changed and were sensitive to the idiosyncratic ways in which these changes had manifested in targets’ behavior

    Regional Integration of Equity Markets in Sub-Saharan Africa

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    Equity markets in developing and emerging economies have grown in number and importance as a result of financial market globalisation. However, their role in economic growth and development is enhanced if nascent markets are integrated with well-established ones. Market integration, measured by the transmission of returns volatility, is identified across a sample of SSA countries, using a unique dataset. Evidence for potential integration between financial markets in Sub-Saharan Africa (SSA) is found. Spillovers are found across markets, some unidirectional and others bi-directional. However, continued illiquidity and incomplete institutions indicate that an integrated financial community remains premature, and considerable regulatory reform and harmonisation will be necessary for this to succeed
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