841 research outputs found

    Nonequilibrium phase transitions and stationary state solutions of a three-dimensional random-field Ising model under a time dependent periodic external field

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    Nonequilibrium behavior and dynamic phase transition properties of a kinetic Ising model under the influence of periodically oscillating random-fields have been analyzed within the framework of effective field theory (EFT) based on a decoupling approximation (DA). Dynamic equation of motion has been solved for a simple cubic lattice (q=6q=6) by utilizing a Glauber type stochastic process. Amplitude of the sinusoidally oscillating magnetic field is randomly distributed on the lattice sites according to bimodal and trimodal distribution functions. For a bimodal type of amplitude distribution, it is found in the high frequency regime that the dynamic phase diagrams of the system in temperature versus field amplitude plane resemble the corresponding phase diagrams of pure kinetic Ising model. Our numerical results indicate that for a bimodal distribution, both in the low and high frequency regimes, the dynamic phase diagrams always exhibit a coexistence region in which the stationary state (ferro or para) of the system is completely dependent on the initial conditions whereas for a trimodal distribution, coexistence region disappears depending on the values of system parameters.Comment: 11 pages, 11 figure

    Narcissus dubius, Narcisse Douteux

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    This species is endemic to southern France and eastern Spain. It is assessed as Least Concern because it has a widespread distribution, occurs in several protected areas throughout its range and its population is not expected to significantly decline in the near future. Further studies on the genetic structure of its population and trends in population size at global level are needed

    Behavior of Reinforced Wall System During the 1999 Kocaeli (Izmit), Turkey, Earthquake

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    A four-span bridge together with a 10 m-high and 100 m-long bridge approach fill was one of the highway facilities damaged due to surface faulting along the Trans-European Motorway during 1999 Kocaeli Earthquake (Mw 7.4). The fault rupture crossed beneath an overpass bridge within a few meters away from the bridge abutment while damaging the approach fill which was reinforced with a double-faced mechanically stabilized earth wall (MSEW) system. The faulting-induced excessive tectonic ground deformations including near-field seismic shakings were the main sources of damage in the walls. Such effects, along with the others, caused cracks and panel separations in wall faces as a result of a liquefaction-induced differential settlement in the cross section. The performance of the reinforced walls was satisfactory that there was no significant structural damage despite the total collapse of the bridge decks. The wall system provided a unique case history under extreme loading conditions, while proving that they are flexible and can withstand large ground deformations. This paper discusses how the walls performed based on post-earthquake reconnaissance studies. The faulting activity, geology of the site, strong ground motions and damage states in the reinforced wall are discussed in details

    Methodology for Evaluation of Seal-Coated, Gravel, and Dirt Roads

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    The objective of this research project was to develop methodologies for the evaluation of different types of seal-coated, gravel, and dirt roads by using a best-practice-oriented pavement-management system in Illinois. A statewide survey comprised of 13 questions collected 133 responses from county engineers and highway commissioners. Many counties and townships in Illinois performed similar practices to maintain seal-coated, gravel, and dirt roads. The subjective windshield surveys were often conducted on a weekly basis to identify the most common distresses, such as potholes, rutting, and roadside drainage. Several seal-coated, gravel, and dirt roads were evaluated using a field distress-survey manual method based on the newly developed Seal-Coated Road Condition Index (SCRCI) and an Unsurfaced-Road Condition Index (URCI) that was adopted to measure surface conditions of gravel and dirt roads. In addition, some of the commercially available cell phone applications, or apps, were investigated for their effectiveness next to the use of a rolling or high-speed profilometer for assessing roughness conditions of seal-coated, gravel, and dirt roads in this research study. Future research is recommended to fully establish guidelines about the use of a cell phone app to be adopted by the Illinois Department of Transportation (IDOT) and for use by local agency officials in Illinois. In conclusion, this research project established a database to develop a best-practice guide for effectively evaluating unpaved roads maintained by local agencies.IDOT-R27-174Ope

    Dynamic phase transition properties and hysteretic behavior of a ferrimagnetic core-shell nanoparticle in the presence of a time dependent magnetic field

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    We have presented dynamic phase transition features and stationary-state behavior of a ferrimagnetic small nanoparticle system with a core-shell structure. By means of detailed Monte Carlo simulations, a complete picture of the phase diagrams and magnetization profiles have been presented and the conditions for the occurrence of a compensation point TcompT_{comp} in the system have been investigated. According to N\'{e}el nomenclature, the magnetization curves of the particle have been found to obey P-type, N-type and Q-type classification schemes under certain conditions. Much effort has been devoted to investigation of hysteretic response of the particle and we observed the existence of triple hysteresis loop behavior which originates from the existence of a weak ferromagnetic core coupling Jc/JshJ_{c}/J_{sh}, as well as a strong antiferromagnetic interface exchange interaction Jint/JshJ_{int}/J_{sh}. Most of the calculations have been performed for a particle in the presence of oscillating fields of very high frequencies and high amplitudes in comparison with exchange interactions which resembles a magnetic system under the influence of ultrafast switching fields. Particular attention has also been paid on the influence of the particle size on the thermal and magnetic properties, as well as magnetic features such as coercivity, remanence and compensation temperature of the particle. We have found that in the presence of ultrafast switching fields, the particle may exhibit a dynamic phase transition from paramagnetic to a dynamically ordered phase with increasing ferromagnetic shell thickness.Comment: 12 pages, 12 figure

    Durability of geothermal grouting materials considering extreme loads

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    The concern about the massive use of the non-renewable and very limited fossil fuels together with the well-known effects of the global warming makes it more necessary the efficient use of the current forms of renewable energy generation. Because of the crucial role played by the grouting materials in the Ground Source Heat Pumps (GSHP), a proper selection of these elements should be made based on a deep knowledge of their performance. In this paper, thermal conductivity, mechanical strength and grout-pipe permeability of four different highly workable grouts have been tested before and after they were subjected to wet-dry and freeze-thaw durability treatments. Results obtained demonstrated the harmful effects of using a large amount of mixing water in grouts subjected to those extreme loads. However, the use of these type of grouts with very good workability is still possible in GSHP installations with balanced thermal designs provided that regular operational and environment conditions are considered.The authors wish to express their gratitude to the Ministry of Economy and Competitiveness which funded this study within the Spanish National Plan for Scientific and Technical Research and Innovation (INNPACTO program) through the research project IPT-2011-0877-920000. The authors are also grateful to all the organizations and companies participating in this project: Sacyr Industrial, Universidad Politécnica de Madrid and Cype

    Dynamic phase transition of the Blume-Capel model in an oscillating magnetic field

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    We employ numerical simulations and finite-size scaling techniques to investigate the properties of the dynamic phase transition that is encountered in the Blume-Capel model subjected to a periodically oscillating magnetic field. We mainly focus on the study of the two-dimensional system for various values of the crystal-field coupling in the second-order transition regime. Our results indicate that the present non-equilibrium phase transition belongs to the universality class of the equilibrium Ising model and allow us to construct a dynamic phase diagram, in analogy to the equilibrium case, at least for the range of parameters considered. Finally, we present some complementary results for the three-dimensional model, where again the obtained estimates for the critical exponents fall into the universality class of the corresponding three-dimensional equilibrium Ising ferromagnet.Comment: 27 pages, 1 table, 15 figures, minor corrections (updated figures 3 and 4
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