470 resultados para Exponents


Relevância:

10.00% 10.00%

Publicador:

Resumo:

Technical and interpretative aspects of the String Quartet No. 2 Guerra-Peixe will approach this work of a composer who is considered one of the greatest exponents of Brazilian music of the twentieth century, who developed several strands in his career as a musicologist, performer, composer, arranger radio and cinema, among others. In this work, we will see in the work in question their compositional styles, pointing sources that he has been drinking and offering elements that will subsidize technical and interpretive choices for future interpreters. After the historical context and esthetics, we will make some brief remarks about the terms performance and interpretation, to support the objective of the work, which will be the interpretation of the work. For that purpose, a comparative analysis was performed between recording of important Brazilian quartets, interviews with relevant players on the national scene and trials in rehearsals and recitals, always making a Quartet bridge with other works by the composer. Concomitantly, it was held analysis of handwritten edits by the composer, culminating with its own revised edition.

Relevância:

10.00% 10.00%

Publicador:

Resumo:

We investigate by means of Monte Carlo simulation and finite-size scaling analysis the critical properties of the three dimensional O (5) non-linear σ model and of the antiferromagnetic RP^(2) model, both of them regularized on a lattice. High accuracy estimates are obtained for the critical exponents, universal dimensionless quantities and critical couplings. It is concluded that both models belong to the same universality class, provided that rather non-standard identifications are made for the momentum-space propagator of the RP^(2) model. We have also investigated the phase diagram of the RP^(2) model extended by a second-neighbor interaction. A rich phase diagram is found, where most of the phase transitions are of the first order.

Relevância:

10.00% 10.00%

Publicador:

Resumo:

The phase diagram of the simplest approximation to double-exchange systems, the bosonic double-exchange model with antiferromagnetic (AFM) superexchange coupling, is fully worked out by means of Monte Carlo simulations, large-N expansions, and variational mean-field calculations. We find a rich phase diagram, with no first-order phase transitions. The most surprising finding is the existence of a segmentlike ordered phase at low temperature for intermediate AFM coupling which cannot be detected in neutron-scattering experiments. This is signaled by a maximum (a cusp) in the specific heat. Below the phase transition, only short-range ordering would be found in neutron scattering. Researchers looking for a quantum critical point in manganites should be wary of this possibility. Finite-size scaling estimates of critical exponents are presented, although large scaling corrections are present in the reachable lattice sizes.

Relevância:

10.00% 10.00%

Publicador:

Resumo:

Tropical Cyclones are a continuing threat to life and property. Willoughby (2012) found that a Pareto (power-law) cumulative distribution fitted to the most damaging 10% of US hurricane seasons fit their impacts well. Here, we find that damage follows a Pareto distribution because the assets at hazard follow a Zipf distribution, which can be thought of as a Pareto distribution with exponent 1. The Z-CAT model is an idealized hurricane catastrophe model that represents a coastline where populated places with Zipf- distributed assets are randomly scattered and damaged by virtual hurricanes with sizes and intensities generated through a Monte-Carlo process. Results produce realistic Pareto exponents. The ability of the Z-CAT model to simulate different climate scenarios allowed testing of sensitivities to Maximum Potential Intensity, landfall rates and building structure vulnerability. The Z-CAT model results demonstrate that a statistical significant difference in damage is found when only changes in the parameters create a doubling of damage.

Relevância:

10.00% 10.00%

Publicador:

Resumo:

The emerging field of quantum thermodynamics is contributing important results and insights into archetypal many-body problems, including quantum phase transitions. Still, the question whether out-of-equilibrium quantities, such as fluctuations of work, exhibit critical scaling after a sudden quench in a closed system has remained elusive. Here, we take a novel approach to the problem by studying a quench across an impurity quantum critical point. By performing density matrix renormalization group computations on the two-impurity Kondo model, we are able to establish that the irreversible work produced in a quench exhibits finite-size scaling at quantum criticality. This scaling faithfully predicts the equilibrium critical exponents for the crossover length and the order parameter of the model, and, moreover, implies a new exponent for the rescaled irreversible work. By connecting the irreversible work to the two-impurity spin correlation function, our findings can be tested experimentally.

Relevância:

10.00% 10.00%

Publicador:

Resumo:

The central interest of this thesis is to comprehend how the public action impels the formation and transformation of the tourist destinies. The research was based on the premise that the public actions are the result of the mediation process of state and non-state actors considered important in a section, which interact aiming for prevailing their interests and world visions above the others. The case of Porto de Galinhas beach, in Pernambuco, locus of the investigation of this thesis, allowed the analysis of a multiplicity of actors on the formation and implementation of local actions toward the development of the tourism between the years 1970 and 2010, as well as permitted the comprehension of the construction of the referential on the interventions made. This thesis, of a qualitative nature, has as theoretical support the cognitive approach of analysis of the public policies developed in France, and it has as main exponents the authors Bruno Jobert and Pierre Muller. This choice was made by the emphasis on the cognitive and normative factors of the politics, which aspects are not very explored in the studies of public policies in Brazil. As the source of the data collection, documental, bibliographic and field researches were utilized to the (re)constitution of the formation and transformation in the site concerned. The analysis techniques applied were the content and the documental analysis. To trace the public action referential, it started by the characterization of the touristic section frontiers and the creation of images by the main international body: the World Tourism Organization, of which analysis of the minutes of the meetings underscored guidelines to the member countries, including Brazil, which compounds the global-sectorial reference of the section. As from the analysis of the evolution of the tourism in the country, was identified that public policies in Brazil passed by transformations in their organization over the years, indicating changes in the referential that guided the interventions. These guidelines and transformations were identified in the construction of the tourist destination of Porto de Galinhas, of which data was systematized and presented in four historical periods, in which were discussed the values, the standard, the algorithms, the images and the important mediators. It has been revealed that the State worked in different roles in the decades analyzed in local tourism. From the 1990s, however, new actors were inserted in the formulation and implementation of policies developed, especially for local hotelkeepers. These, through their association, establishes a leadership relation in the local touristic section, thereby, they could set their hegemony and spread their own interest. The leadership acquired by a group of actors, in the case of Porto de Galinhas, does not mean that trade within the industry were neutralized, but that there is a cognitive framework that confronts the actors involved. In spite of the advances achieved by the work of the mediators in the last decades, that resulted in an amplification and diversification of the activity in the area, as well as the consolidation at the beach, as a tourist destiny of national standout, the position of the place is instable, concerned to the competitiveness, once that there is an situation of social and environmental unsustainability

Relevância:

10.00% 10.00%

Publicador:

Resumo:

Thesis (Ph.D.)--University of Washington, 2016-07

Relevância:

10.00% 10.00%

Publicador:

Resumo:

In this thesis the critical dynamics of several magnetoelectric compounds at their phase transition were examined. Mostly measurements of the dielectric properties in the frequency range of below 1 Hz up to 5 GHz were employed to evaluate the critical exponents for both magnetic field and temperature-dependent measurements. Most of the materials that are part of this work show anomalous behavior, especially at very low temperatures where quantum fluctuations are of the order of or even dominate those induced thermally. This anomalous behavior manifests in different forms. In Dy2Ti2O7 we demonstrate the existence of electric dipoles on magnetic monopoles. Here the dynamics at the critical endpoint located at 0.36K and in a magnetic field of 1T parallel to the [111] direction are of special interest. At this critical endpoint the expected critical slowing down of the dynamics could not only not be observed but instead the opposite, critical speeding-up by several orders of magnitude, could be demonstrated. Furthermore, we show that the phase diagram of Dy2Ti2O7 in this field direction can be reproduced solely from the dynamical properties, for example the resonance frequency of the observed relaxation that is connected to the monopole movement. Away from this point of the phase diagram the dynamics are slowing-down with reduction of temperature as one would expect. Additional measurements on Y2Ti2O7, a structurally identical but non-magnetic material, show only slowing down with reduction of temperature and no additional features. A possible explanation for the observed critical speeding-up is a coherent movement of magnetic monopoles close to the critical field that increases the resonance frequency by reducing the damping of the process. LiCuVO4 on the other hand behaves normally at its phase transition as long as the temperature is higher than 0.4 K. In this temperature regime the dynamics show critical slowing-down analogous to classical ferroelectric materials. This analogy extends also towards higher frequencies where the permittivity displays a ‘dispersion’ minimum that is temperature-dependent but of the order of 2 GHz. Below 0.4K the observed behavior changes drastically. Here we found no longer relaxational behavior but instead an excitation with very low energy. This low energy excitation was predicted by theory and is caused by nearly gapless soliton excitations within the 1D Cu2+ chains of LiCuVO4. Finally, in TbMnO3 the dynamics of the phase transition into the multiferroic phase was observed at roughly 27 K, a much higher temperature compared to the other materials. Here the expected critical slowing-down was observed, even though in low-frequency measurements this transition into the ferroelectric phase is overshadowed by the so-called c-axis relaxation. Therefore, only frequencies above 1MHz could be used to determine the critical exponents for both temperatureand magnetic-field-dependent measurements. This was done for both the peak frequency as well as the relaxation strength. In TbMnO3 an electromagnetic soft-mode with small optical weight causes the observed fluctuations, similar to the case of multiferroic MnWO4.

Relevância:

10.00% 10.00%

Publicador:

Resumo:

A two stage approach to performing ab initio calculations on medium and large sized molecules is described. The first step is to perform SCF calculations on small molecules or molecular fragments using the OPIT Program. This employs a small basis set of spherical and p-type Gaussian functions. The Gaussian functions can be identified very closely with atomic cores, bond pairs, lone pairs, etc. The position and exponent of any of the Gaussian functions can be varied by OPIT to produce a small but fully optimised basis set. The second stage is the molecular fragments method. As an example of this, Gaussian exponents and distances are taken from an OPIT calculation on ethylene and used unchanged in a single SCF calculation on benzene. Approximate ab initio calculations of this type give much useful information and are often preferable to semi-empirical approaches, since the nature of the approximations involved is much better defined.

Relevância:

10.00% 10.00%

Publicador:

Resumo:

Chains of interacting non-Abelian anyons with local interactions invariant under the action of the Drinfeld double of the dihedral group D-3 are constructed. Formulated as a spin chain the Hamiltonians are generated from commuting transfer matrices of an integrable vertex model for periodic and braided as well as open boundaries. A different anyonic model with the same local Hamiltonian is obtained within the fusion path formulation. This model is shown to be related to an integrable fusion interaction round the face model. Bulk and surface properties of the anyon chain are computed from the Bethe equations for the spin chain. The low-energy effective theories and operator content of the models (in both the spin chain and fusion path formulation) are identified from analytical and numerical studies of the finite-size spectra. For all boundary conditions considered the continuum theory is found to be a product of two conformal field theories. Depending on the coupling constants the factors can be a Z(4) parafermion or a M-(5,M-6) minimal model.

Relevância:

10.00% 10.00%

Publicador:

Resumo:

This dissertation has two almost unrelated themes: privileged words and Sturmian words. Privileged words are a new class of words introduced recently. A word is privileged if it is a complete first return to a shorter privileged word, the shortest privileged words being letters and the empty word. Here we give and prove almost all results on privileged words known to date. On the other hand, the study of Sturmian words is a well-established topic in combinatorics on words. In this dissertation, we focus on questions concerning repetitions in Sturmian words, reproving old results and giving new ones, and on establishing completely new research directions. The study of privileged words presented in this dissertation aims to derive their basic properties and to answer basic questions regarding them. We explore a connection between privileged words and palindromes and seek out answers to questions on context-freeness, computability, and enumeration. It turns out that the language of privileged words is not context-free, but privileged words are recognizable by a linear-time algorithm. A lower bound on the number of binary privileged words of given length is proven. The main interest, however, lies in the privileged complexity functions of the Thue-Morse word and Sturmian words. We derive recurrences for computing the privileged complexity function of the Thue-Morse word, and we prove that Sturmian words are characterized by their privileged complexity function. As a slightly separate topic, we give an overview of a certain method of automated theorem-proving and show how it can be applied to study privileged factors of automatic words. The second part of this dissertation is devoted to Sturmian words. We extensively exploit the interpretation of Sturmian words as irrational rotation words. The essential tools are continued fractions and elementary, but powerful, results of Diophantine approximation theory. With these tools at our disposal, we reprove old results on powers occurring in Sturmian words with emphasis on the fractional index of a Sturmian word. Further, we consider abelian powers and abelian repetitions and characterize the maximum exponents of abelian powers with given period occurring in a Sturmian word in terms of the continued fraction expansion of its slope. We define the notion of abelian critical exponent for Sturmian words and explore its connection to the Lagrange spectrum of irrational numbers. The results obtained are often specialized for the Fibonacci word; for instance, we show that the minimum abelian period of a factor of the Fibonacci word is a Fibonacci number. In addition, we propose a completely new research topic: the square root map. We prove that the square root map preserves the language of any Sturmian word. Moreover, we construct a family of non-Sturmian optimal squareful words whose language the square root map also preserves.This construction yields examples of aperiodic infinite words whose square roots are periodic.

Relevância:

10.00% 10.00%

Publicador:

Resumo:

The central interest of this thesis is to comprehend how the public action impels the formation and transformation of the tourist destinies. The research was based on the premise that the public actions are the result of the mediation process of state and non-state actors considered important in a section, which interact aiming for prevailing their interests and world visions above the others. The case of Porto de Galinhas beach, in Pernambuco, locus of the investigation of this thesis, allowed the analysis of a multiplicity of actors on the formation and implementation of local actions toward the development of the tourism between the years 1970 and 2010, as well as permitted the comprehension of the construction of the referential on the interventions made. This thesis, of a qualitative nature, has as theoretical support the cognitive approach of analysis of the public policies developed in France, and it has as main exponents the authors Bruno Jobert and Pierre Muller. This choice was made by the emphasis on the cognitive and normative factors of the politics, which aspects are not very explored in the studies of public policies in Brazil. As the source of the data collection, documental, bibliographic and field researches were utilized to the (re)constitution of the formation and transformation in the site concerned. The analysis techniques applied were the content and the documental analysis. To trace the public action referential, it started by the characterization of the touristic section frontiers and the creation of images by the main international body: the World Tourism Organization, of which analysis of the minutes of the meetings underscored guidelines to the member countries, including Brazil, which compounds the global-sectorial reference of the section. As from the analysis of the evolution of the tourism in the country, was identified that public policies in Brazil passed by transformations in their organization over the years, indicating changes in the referential that guided the interventions. These guidelines and transformations were identified in the construction of the tourist destination of Porto de Galinhas, of which data was systematized and presented in four historical periods, in which were discussed the values, the standard, the algorithms, the images and the important mediators. It has been revealed that the State worked in different roles in the decades analyzed in local tourism. From the 1990s, however, new actors were inserted in the formulation and implementation of policies developed, especially for local hotelkeepers. These, through their association, establishes a leadership relation in the local touristic section, thereby, they could set their hegemony and spread their own interest. The leadership acquired by a group of actors, in the case of Porto de Galinhas, does not mean that trade within the industry were neutralized, but that there is a cognitive framework that confronts the actors involved. In spite of the advances achieved by the work of the mediators in the last decades, that resulted in an amplification and diversification of the activity in the area, as well as the consolidation at the beach, as a tourist destiny of national standout, the position of the place is instable, concerned to the competitiveness, once that there is an situation of social and environmental unsustainability

Relevância:

10.00% 10.00%

Publicador:

Resumo:

This work aims to study the fluctuation structure of physical properties of oil well profiles. It was used as technique the analysis of fluctuations without trend (Detrended Fluctuation Analysis - DFA). It has been made part of the study 54 oil wells in the Campo de Namorado located in the Campos Basin in Rio de Janeiro. We studied five sections, namely: sonic, density, porosity, resistivity and gamma rays. For most of the profiles , DFA analysis was available in the literature, though the sonic perfile was estimated with the aid of a standard algorithm. The comparison between the exponents of DFA of the five profiles was performed using linear correlation of variables, so we had 10 comparisons of profiles. Our null hypothesis is that the values of DFA for the various physical properties are independent. The main result indicates that no refutation of the null hypothesis. That is, the fluctuations observed by DFA in the profiles do not have a universal character, that is, in general the quantities display a floating structure of their own. From the ten correlations studied only the profiles of density and sonic one showed a significant correlation (p> 0.05). Finally these results indicate that one should use the data from DFA with caution, because, in general, based on geological analysis DFA different profiles can lead to disparate conclusions

Relevância:

10.00% 10.00%

Publicador:

Resumo:

The study of complex systems has become a prestigious area of science, although relatively young . Its importance was demonstrated by the diversity of applications that several studies have already provided to various fields such as biology , economics and Climatology . In physics , the approach of complex systems is creating paradigms that influence markedly the new methods , bringing to Statistical Physics problems macroscopic level no longer restricted to classical studies such as those of thermodynamics . The present work aims to make a comparison and verification of statistical data on clusters of profiles Sonic ( DT ) , Gamma Ray ( GR ) , induction ( ILD ) , neutron ( NPHI ) and density ( RHOB ) to be physical measured quantities during exploratory drilling of fundamental importance to locate , identify and characterize oil reservoirs . Software were used : Statistica , Matlab R2006a , Origin 6.1 and Fortran for comparison and verification of the data profiles of oil wells ceded the field Namorado School by ANP ( National Petroleum Agency ) . It was possible to demonstrate the importance of the DFA method and that it proved quite satisfactory in that work, coming to the conclusion that the data H ( Hurst exponent ) produce spatial data with greater congestion . Therefore , we find that it is possible to find spatial pattern using the Hurst coefficient . The profiles of 56 wells have confirmed the existence of spatial patterns of Hurst exponents , ie parameter B. The profile does not directly assessed catalogs verification of geological lithology , but reveals a non-random spatial distribution

Relevância:

10.00% 10.00%

Publicador:

Resumo:

The pair contact process - PCP is a nonequilibrium stochastic model which, like the basic contact process - CP, exhibits a phase transition to an absorbing state. While the absorbing state CP corresponds to a unique configuration (empty lattice), the PCP process infinitely many. Numerical and theoretical studies, nevertheless, indicate that the PCP belongs to the same universality class as the CP (direct percolation class), but with anomalies in the critical spreading dynamics. An infinite number of absorbing configurations arise in the PCP because all process (creation and annihilation) require a nearest-neighbor pair of particles. The diffusive pair contact process - PCPD) was proposed by Grassberger in 1982. But the interest in the problem follows its rediscovery by the Langevin description. On the basis of numerical results and renormalization group arguments, Carlon, Henkel and Schollwöck (2001), suggested that certain critical exponents in the PCPD had values similar to those of the party-conserving - PC class. On the other hand, Hinrichsen (2001), reported simulation results inconsistent with the PC class, and proposed that the PCPD belongs to a new universality class. The controversy regarding the universality of the PCPD remains unresolved. In the PCPD, a nearest-neighbor pair of particles is necessary for the process of creation and annihilation, but the particles to diffuse individually. In this work we study the PCPD with diffusion of pair, in which isolated particles cannot move; a nearest-neighbor pair diffuses as a unit. Using quasistationary simulation, we determined with good precision the critical point and critical exponents for three values of the diffusive probability: D=0.5 and D=0.1. For D=0.5: PC=0.89007(3), β/v=0.252(9), z=1.573(1), =1.10(2), m=1.1758(24). For D=0.1: PC=0.9172(1), β/v=0.252(9), z=1.579(11), =1.11(4), m=1.173(4)