1,619 research outputs found

    Interpolation Properties and SAT-based Model Checking

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    Craig interpolation is a widespread method in verification, with important applications such as Predicate Abstraction, CounterExample Guided Abstraction Refinement and Lazy Abstraction With Interpolants. Most state-of-the-art model checking techniques based on interpolation require collections of interpolants to satisfy particular properties, to which we refer as "collectives"; they do not hold in general for all interpolation systems and have to be established for each particular system and verification environment. Nevertheless, no systematic approach exists that correlates the individual interpolation systems and compares the necessary collectives. This paper proposes a uniform framework, which encompasses (and generalizes) the most common collectives exploited in verification. We use it for a systematic study of the collectives and of the constraints they pose on propositional interpolation systems used in SAT-based model checking

    Virtual Enterprises Risk Management DSS under Electronic Commerce

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    Risk management is important to the development of enterprise as well as social-economic prosperity. Virtual enterprise is the potential mode of future enterprise under electronic commerce environment and the risk management for it is a popular research area recently. Due to the complexity of its risk management a decision support system (DSS) with 3-bases-1-cell structure was designed. By coordinating data base, model base, algorithm base and dialogue cell, the functions of project management, risk identification, risk assessment, risk evaluation and risk programming was supported. The user-friendly system has such main characteristics as generality for verity virtual enterprise as well as different projects and the flexibility of model and algorithm, ensuring a standardized, scientific and informational risk management for virtual enterprises

    A Risk Identification Method of Virtual Enterprise

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    Virtual enterprise is the potential mode of future enterprise under global economic environment and the risk management for it is a popular research area recently. Risk identification is the key phrase of risk management. Considering the risk identification problem in the virtual enterprise, a new identification method based on the BP network is provided in this paper. Using this method and the data related to the problem, the possible to take place of the risks could be obtained by training the neural network, so that risks can be investigated in time and managed effectively. The simulation results prove its validit

    Evolution of Non-Equilibrium Profile in Adsorbate Layer under Compressive Strain

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    We investigate the time evolution of an initial step profile separating a bare substrate region from the rest of the compressively strained adsorbate layer near a commensurate to incommensurate transition. The rate of profile evolution as a function of the mismatch, coverage and the strength of the substrate potential are determined by Brownian molecular dynamics simulations. We find that the results are qualitatively similar to those observed for the Pb/Si(111) system. The anomalously fast time evolution and sharpness of the non-equilibrium profile can be understood through the domain wall creation at the boundary and its subsequent diffusion into the interior of the adsorbate layer.Comment: 6 pages, 7 figures, Tribology Letter

    Search for Invisible Decays of η\eta and η′\eta^\prime in J/ψ→ϕηJ/\psi \to \phi\eta and ϕη′\phi \eta^\prime

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    Using a data sample of 58×10658\times 10^6 J/ψJ/\psi decays collected with the BES II detector at the BEPC, searches for invisible decays of η\eta and η′\eta^\prime in J/ψJ/\psi to ϕη\phi\eta and ϕη′\phi\eta^\prime are performed. The ϕ\phi signals, which are reconstructed in K+K−K^+K^- final states, are used to tag the η\eta and η′\eta^\prime decays. No signals are found for the invisible decays of either η\eta or η′\eta^\prime, and upper limits at the 90% confidence level are determined to be 1.65×10−31.65 \times 10^{-3} for the ratio B(η→invisible)B(η→γγ)\frac{B(\eta\to \text{invisible})}{B(\eta\to\gamma\gamma)} and 6.69×10−26.69\times 10^{-2} for B(η′→invisible)B(η′→γγ)\frac{B(\eta^\prime\to \text{invisible})}{B(\eta^\prime\to\gamma\gamma)}. These are the first searches for η\eta and η′\eta^\prime decays into invisible final states.Comment: 5 pages, 4 figures; Added references, Corrected typo

    Backward pion-nucleon scattering

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    A global analysis of the world data on differential cross sections and polarization asymmetries of backward pion-nucleon scattering for invariant collision energies above 3 GeV is performed in a Regge model. Including the NαN_\alpha, NγN_\gamma, Δδ\Delta_\delta and Δβ\Delta_\beta trajectories, we reproduce both angular distributions and polarization data for small values of the Mandelstam variable uu, in contrast to previous analyses. The model amplitude is used to obtain evidence for baryon resonances with mass below 3 GeV. Our analysis suggests a G39G_{39} resonance with a mass of 2.83 GeV as member of the Δβ\Delta_{\beta} trajectory from the corresponding Chew-Frautschi plot.Comment: 12 pages, 16 figure

    Believability of cigarette warnings about addiction: National experiments of adolescents and adults

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    Introduction: We conducted two experiments to examine the believability of three addictionfocused cigarette warnings and the influence of message source on believability among adolescents and adults in the United States. Methods: Experimental data were collected using national phone surveys of adolescents (age 13-17; n = 1125; response rate, 66%) and adults (age 18+; n = 5014; response rate, 42%). We assessed the believability of three cigarette warnings about addiction attributed to four message sources (Food and Drug Administration [FDA], Surgeon General, Centers for Disease Control and Prevention [CDC], no source). Results: The majority of adolescents and adults reported the three cigarette warnings were very believable (49%-81% for adolescents; 47%-76% for adults). We found four to five times higher odds of adolescents believing a warning that cigarettes are addictive (warning 1) or that nicotine was an addictive chemical (warning 2) compared to a warning that differentiated the addictive risks of menthol versus traditional cigarettes (warning 3), warning 1 adjusted odds ratio (aOR): 4.53, 95% confidence interval (CI): 3.10, 6.63; warning 2 aOR: 3.87, 95% CI: 2.70, 5.50. Similarly, we found three to five times higher odds of adults (including current smokers) believing the same warnings, warning 1 aOR: 3.74, 95% CI: 2.82, 4.95; warning 2 aOR: 3.24, 95% CI: 2.45, 4.28. Message source had no overall impact on the believability of warnings for either population. Conclusions: Our findings support the implementation of FDA's required warnings that cigarettes are addictive and that nicotine is an addictive chemical. These believable warnings may deter adolescents from initiating smoking and encourage adults to quit smoking. Implications: This article describes, for the first time, the believability of different cigarette warnings about addiction. We now know that the majority of adolescents and adults believe cigarette warnings that highlight cigarettes as addictive and that nicotine is an addictive chemical in tobacco. However, a warning that highlighted the relative risk of addiction for menthol cigarettes compared to traditional cigarettes was not as believable among either population. Our findings support the implementation of FDA's required warnings that cigarettes are addictive and that nicotine is an addictive chemical that may deter adolescents from initiating smoking and encourage adults to quit smoking

    Creating sustainable value through food waste management: does retail customer value proposition matter?

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    Purpose This research aims to explore retail managers' views on how food waste (FW) management activities contribute to sustainable value creation and how the customer value proposition (CVP) for a given food retailer interacts with their approaches to FW management. Design/methodology/approach A three-stage exploratory qualitative approach to data collection and analysis was adopted, involving in-depth interviews with retail managers, documentary analysis of multiple years of relevant corporate reports and email validation by seven major UK grocery retailers. Thematic content analysis supplemented by word similarity cluster analysis, two-step cluster analysis and crisp-set qualitative comparative analysis was undertaken. Findings FW management practices have been seen by retail managers to contribute to all forms of sustainable value creation, as waste reduction minimises environmental impact, saves costs and/or serves social needs, whilst economic value creation lies at the heart of retail FW management. However, retail operations are also framed by CVP and size of a retailer that enable or inhibit the adoption of certain FW management practices. Low-price retailers were more likely to adopt practices enabling them to save costs. Complicated cost-incurring solutions to FW were more likely to be adopted by retailers associated with larger size, high quality and a range of services. Originality/value This study is the first of its kind to empirically explore retail managers' perception of sustainable value creation through FW management activities and to provide empirical evidence of the linkages between retail CVP and sustainable value creation in the context of retail FW management

    Observation of Two New N* Peaks in J/psi -> ppi−nˉp pi^- \bar n and pˉπ+n\bar p\pi^+n Decays

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    The πN\pi N system in decays of J/ψ→NˉNπJ/\psi\to\bar NN\pi is limited to be isospin 1/2 by isospin conservation. This provides a big advantage in studying N∗→πNN^*\to \pi N compared with πN\pi N and γN\gamma N experiments which mix isospin 1/2 and 3/2 for the πN\pi N system. Using 58 million J/ψJ/\psi decays collected with the Beijing Electron Positron Collider, more than 100 thousand J/ψ→pπ−nˉ+c.c.J/\psi \to p \pi^- \bar n + c.c. events are obtained. Besides two well known N∗N^* peaks at 1500 MeV and 1670 MeV, there are two new, clear N∗N^* peaks in the pπp\pi invariant mass spectrum around 1360 MeV and 2030 MeV. They are the first direct observation of the N∗(1440)N^*(1440) peak and a long-sought "missing" N∗N^* peak above 2 GeV in the πN\pi N invariant mass spectrum. A simple Breit-Wigner fit gives the mass and width for the N∗(1440)N^*(1440) peak as 1358±6±161358\pm 6 \pm 16 MeV and 179±26±50179\pm 26\pm 50 MeV, and for the new N∗N^* peak above 2 GeV as 2068±3−40+152068\pm 3^{+15}_{-40} MeV and 165±14±40165\pm 14\pm 40 MeV, respectively
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