1,122 research outputs found

    Pattern Stability and Trijunction Motion in Eutectic Solidification

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    We demonstrate by both experiments and phase-field simulations that lamellar eutectic growth can be stable for a wide range of spacings below the point of minimum undercooling at low velocity, contrary to what is predicted by existing stability analyses. This overstabilization can be explained by relaxing Cahn's assumption that lamellae grow locally normal to the eutectic interface.Comment: 4 pages, 5 eps figure

    Resource dedication problem in a multi-project environment

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    There can be different approaches to the management of resources within the context of multi-project scheduling problems. In general, approaches to multiproject scheduling problems consider the resources as a pool shared by all projects. On the other hand, when projects are distributed geographically or sharing resources between projects is not preferred, then this resource sharing policy may not be feasible. In such cases, the resources must be dedicated to individual projects throughout the project durations. This multi-project problem environment is defined here as the resource dedication problem (RDP). RDP is defined as the optimal dedication of resource capacities to different projects within the overall limits of the resources and with the objective of minimizing a predetermined objective function. The projects involved are multi-mode resource constrained project scheduling problems with finish to start zero time lag and non-preemptive activities and limited renewable and nonrenewable resources. Here, the characterization of RDP, its mathematical formulation and two different solution methodologies are presented. The first solution approach is a genetic algorithm employing a new improvement move called combinatorial auction for RDP, which is based on preferences of projects for resources. Two different methods for calculating the projects’ preferences based on linear and Lagrangian relaxation are proposed. The second solution approach is a Lagrangian relaxation based heuristic employing subgradient optimization. Numerical studies demonstrate that the proposed approaches are powerful methods for solving this problem

    Neutrinos below 100 TeV from the southern sky employing refined veto techniques to IceCube data

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    Many Galactic sources of gamma rays, such as supernova remnants, are expected to produce neutrinos with a typical energy cutoff well below 100 TeV. For the IceCube Neutrino Observatory located at the South Pole, the southern sky, containing the inner part of the Galactic plane and the Galactic Center, is a particularly challenging region at these energies, because of the large background of atmospheric muons. In this paper, we present recent advancements in data selection strategies for track-like muon neutrino events with energies below 100 TeV from the southern sky. The strategies utilize the outer detector regions as veto and features of the signal pattern to reduce the background of atmospheric muons to a level which, for the first time, allows IceCube searching for point-like sources of neutrinos in the southern sky at energies between 100 GeV and several TeV in the muon neutrino charged current channel. No significant clustering of neutrinos above background expectation was observed in four years of data recorded with the completed IceCube detector. Upper limits on the neutrino flux for a number of spectral hypotheses are reported for a list of astrophysical objects in the southern hemisphere.Comment: 19 pages, 17 figures, 2 table

    Thermal fluctuations on the freeze-out surface of heavy-ion collisions and their impact on particle correlations

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    Particle momentum distributions originating from a quark-gluon plasma asproduced in high-energy nuclear collisions can be influenced by thermalfluctuations in fluid dynamic fields. We study this effect by generalizing thecommonly used kinetic freeze-out prescription by allowing for smallfluctuations around an average in fluid velocity, chemical potentials andtemperature. This leads to the appearance of specific two-body momentumcorrelations. Combining a blast-wave parametrization of the kinetic freeze-outsurface with the thermal correlation functions of an ideal resonance gas, weperform an exploratory study of angular net-charge correlations induced bythermal fluctuations around vanishing chemical potential. We note a diffusionof the near-side peak around Δy=Δϕ=0\Delta y=\Delta\phi=0 induced by variances ofdifferent chemical potentials, which could be investigated experimentally.<br

    3-MCPD and glycidol levels in edible oils and fats obtained from local markets in Türkiye

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    In this study, it was aimed to determine the 3-MCPD and glycidol levels in 9 types (46 brands) of edible fat and oil offered for sale in markets located in Türkiye. 3-MCPD and glycidol levels were determined by making some modifications to the DGF C VI 18 (10) method. The highest levels of 3-MCPD and glycidol levels were detected in hazelnut oils, riviera olive oils, margarines, and shortenings. As expected, these contaminants were not observed in extra-virgin olive oils, while they were detected at low levels in fish oils. The highest 3-MCPD levels were found in the range of 0.06-2.12 mg·kg-1 in hazelnut oil, 0.16-1.69 mg·kg-1 in riviera olive oils, and 0.17-1.17 mg·kg-1 in margarines. The highest glycidol levels were found in the shortenings in the range of 1.98-6.46 mg·kg-1, followed by hazelnut oil (0.54-2.63 mg·kg-1) and riviera olive oil (0.19-3.53 mg·kg-1)

    The application of disaster management in Turkey from a comparative perspective: A proposal for a new model

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    Bu çalışma, 13-15 Eylül 2010 tarihleri arasında Algarve[Portekiz]’da düzenlenen 7. International Conference on Computer Simulation in Risk Analysis and Hazard Mitigation’da bildiri olarak sunulmuştur.This study examines the mutual relations between risk, risk society and types of disaster, after having defined risk and the risk society, then proceeding to analyze a range of disaster management models that are currently applied in Turkey and other countries. An empirical survey about the last major disaster that occurred in Turkey is carried out. Consequently, a new, effective and functional integrated disaster management model for Turkey is proposed. The term 'risk society' describes the inevitable new hazards produced by industrial society's process of development. The risk society brings not only hazards and risks that are not familiar and have not been faced before, but also prosperity and benefits for the members of the risk society. Natural and man-made disasters affect human beings more than in pre-industrial society and produce distinctive impacts on and changes in the psychological structure of urban society after disasters. The disaster management system applied in the risk society should be different from classical systems. While implementing a disaster management model, specific types of disaster that may occur in urban areas should be considered. The model should include swift response, efficiency and practicality. As a conclusion of all these studies, a new, effective disaster management model applicable to Turkey is proposed.Wessex Inst TechnolWit, Transact Ecol & Environ
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