15 resultados para Forças críticas
em Universidade Federal do Rio Grande do Norte(UFRN)
Resumo:
PEDRO, Edilson da Silva. Estratégias para a organização da pesquisa em cana-de-açúcar: uma análise de governança em sistemas de inovação. 2008. 226f. Tese (Doutorado em Política Científica e Tecnológica) - Universidade Estadual de Campinas, Campinas, 2008.
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)
Resumo:
This work was developed in the research line: "The habitus of study: builder of a new reality in the basic education of metropolitan area Natal" which is being developed with the support of CAPES by the Centre for Education. Acts, especially the problem of academic performance of students in basic education of the public in the Metropolitan Region of Natal (RMN). Thus, the aim of this paper is to construct a typology of students in the 9th year of basic education, attending the public schools (state or municipal) of MRN, 2009, and assess, according to these profiles, what personal characteristics student and their families: economic, social and cultural capital as well as teaching practices create environments capable of favoring a good educational development as measured by the performance obtained in the assessments in mathematics and English language. The data used were provided through the microdata Brazil Exam 2009 held by INEP. We used the methods Grade of Membership (GoM) for construction of profiles relevance of students according to the characteristics already mentioned. With these profiles was verified, which were effectively generating good performance in school curriculum components evaluated. The findings indicate that students belonging to the profile considered good environment, able to achieve better school performance both in Portuguese as in Mathematics, compared to the extreme profiles and adverse deficit
Resumo:
We study the critical behavior of the one-dimensional pair contact process (PCP), using the Monte Carlo method for several lattice sizes and three different updating: random, sequential and parallel. We also added a small modification to the model, called Monte Carlo com Ressucitamento" (MCR), which consists of resuscitating one particle when the order parameter goes to zero. This was done because it is difficult to accurately determine the critical point of the model, since the order parameter(particle pair density) rapidly goes to zero using the traditional approach. With the MCR, the order parameter becomes null in a softer way, allowing us to use finite-size scaling to determine the critical point and the critical exponents β, ν and z. Our results are consistent with the ones already found in literature for this model, showing that not only the process of resuscitating one particle does not change the critical behavior of the system, it also makes it easier to determine the critical point and critical exponents of the model. This extension to the Monte Carlo method has already been used in other contact process models, leading us to believe its usefulness to study several others non-equilibrium models
Resumo:
In this work we study a connection between a non-Gaussian statistics, the Kaniadakis
statistics, and Complex Networks. We show that the degree distribution P(k)of
a scale free-network, can be calculated using a maximization of information entropy in
the context of non-gaussian statistics. As an example, a numerical analysis based on the
preferential attachment growth model is discussed, as well as a numerical behavior of
the Kaniadakis and Tsallis degree distribution is compared. We also analyze the diffusive
epidemic process (DEP) on a regular lattice one-dimensional. The model is composed
of A (healthy) and B (sick) species that independently diffusive on lattice with diffusion
rates DA and DB for which the probabilistic dynamical rule A + B → 2B and B → A. This
model belongs to the category of non-equilibrium systems with an absorbing state and a
phase transition between active an inactive states. We investigate the critical behavior of
the DEP using an auto-adaptive algorithm to find critical points: the method of automatic
searching for critical points (MASCP). We compare our results with the literature and we
find that the MASCP successfully finds the critical exponents 1/ѵ and 1/zѵ in all the cases
DA =DB, DA
Resumo:
A real space renormalization group method is used to investigate the criticality (phase diagrams, critical expoentes and universality classes) of Z(4) model in two and three dimensions. The values of the interaction parameters are chosen in such a way as to cover the complete phase diagrams of the model, which presents the following phases: (i) Paramagnetic (P); (ii) Ferromagnetic (F); (iii) Antiferromagnetic (AF); (iv) Intermediate Ferromagnetic (IF) and Intermediate Antiferromagnetic (IAF). In the hierarquical lattices, generated by renormalization the phase diagrams are exact. It is also possible to obtain approximated results for square and simple cubic lattices. In the bidimensional case a self-dual lattice is used and the resulting phase diagram reproduces all the exact results known for the square lattice. The Migdal-Kadanoff transformation is applied to the three dimensional case and the additional phases previously suggested by Ditzian et al, are not found
Resumo:
The new technique for automatic search of the order parameters and critical properties is applied to several well-know physical systems, testing the efficiency of such a procedure, in order to apply it for complex systems in general. The automatic-search method is combined with Monte Carlo simulations, which makes use of a given dynamical rule for the time evolution of the system. In the problems inves¬tigated, the Metropolis and Glauber dynamics produced essentially equivalent results. We present a brief introduction to critical phenomena and phase transitions. We describe the automatic-search method and discuss some previous works, where the method has been applied successfully. We apply the method for the ferromagnetic fsing model, computing the critical fron¬tiers and the magnetization exponent (3 for several geometric lattices. We also apply the method for the site-diluted ferromagnetic Ising model on a square lattice, computing its critical frontier, as well as the magnetization exponent f3 and the susceptibility exponent 7. We verify that the universality class of the system remains unchanged when the site dilution is introduced. We study the problem of long-range bond percolation in a diluted linear chain and discuss the non-extensivity questions inherent to long-range-interaction systems. Finally we present our conclusions and possible extensions of this work
Resumo:
In this thesis, we address two issues of broad conceptual and practical relevance in the study of complex networks. The first is associated with the topological characterization of networks while the second relates to dynamical processes that occur on top of them. Regarding the first line of study, we initially designed a model for networks growth where preferential attachment includes: (i) connectivity and (ii) homophily (links between sites with similar characteristics are more likely). From this, we observe that the competition between these two aspects leads to a heterogeneous pattern of connections with the topological properties of the network showing quite interesting results. In particular, we emphasize that there is a region where the characteristics of sites play an important role not only for the rate at which they get links, but also for the number of connections which occur between sites with similar and dissimilar characteristics. Finally, we investigate the spread of epidemics on the network topology developed, whereas its dissemination follows the rules of the contact process. Using Monte Carlo simulations, we show that the competition between states (infected/healthy) sites, induces a transition between an active phase (presence of sick) and an inactive (no sick). In this context, we estimate the critical point of the transition phase through the cumulant Binder and ratio between moments of the order parameter. Then, using finite size scaling analysis, we determine the critical exponents associated with this transition
Resumo:
Conselho Nacional de Desenvolvimento Científico e Tecnológico
Resumo:
This work has as object of study the Hospital de Caridade Juvino Barreto, nosocomial institution located in the city of Natal (RN), between the Praia de Areia Preta and the Monte Petrópolis, focusing on the period from 1909, the year in which the new hospital building was constructed and opened, and 1927, the date of the transfer of administration of the public domain to the newly created Sociedade de Assistência Hospitalar (SAH). We study the conditions of possibility of the emergence of this hospital space in the urban environment of the capital of Rio Grande do Norte, seeking to understand the different tactics and strategies implemented by the historical subjects involved in the formation of this institution nosocomial. Starting from a corpus of documents consisting of medical memories (with Dr. Januário Cicco as privileged observer), information present in newspapers (the Republic and the Christmas Journa l), photo collection and extensive administrative and legal material (Speeches, Exhibitions, Reports, Laws and Resolutions), we analyzed in detail the medical geography of HCJB, relating the discourses of medicine and geography in choosing the spatial location of the hospital as we examine the architecture of the hospital, its inner spat iality, divisions, forms of space control, and, finally, we discuss the medical practices that took place within it, leading us in this regard, from the experiences of clinical hospital chief, Dr. Januário Cicco, especially the discussion on "ethics" in hospital work. The perception of HCJB as medical nosoespaciality always on the move, incorporated under taxonomic principles based on difference and dispersion forces, led us to articulate it theoretically from the conceptual-methodological arsenal of philosopher Michel Foucault, particularly his reflections of genealogical phase, focusing on the phenomenon of power, a position that allows us to enhance our space-hospital construction, invention, product of power relations, which give the unfinished aspect nosocômio, apparent, always at stake, perpetual non-modeling possibility has previously defined array, establishing it at the field of possible, of virtuality, of power: hospital that could have been and that it was not. Indeed, the investigation of various aspects/elements of hospital space Juvino Barreto revealed us new dimensions of hospital space, far more complex than the simple and the current idea of a place to shelter patients: plasticity and fluidity of space, which is not made to circumscribe the limits of empeiria, engraving up to strength relations fought between different subject; its Constitution as a transitional space, Heterotopic, doing live inside modern elements with premoderns (professional doctors working with religious thought, skeptical of positivist medicine living with the religious faith of the nuns of Santana); the impossibility of thinking hospital space of HCJB while homogeneous unit, static, transistoric, making the spatiality, without considering the profound differences, fractures and dislocations that animated his own existence, multiplying their expressions of identity
Resumo:
The problematic that gives shape to this research is the question of the historical process of demobilization of the movement of the working classes in your accented contemporary moment. Their object of study, however, and that it particularizes, it relates to a portion this problematic; it relates to set of determinations that comprise a broader set of determinations of this historical process: it is a set of determinations forged and mediated by bourgeois strategies of management for the conformation of the circumstances necessary for the domination and for the conduct of labor force on operations in work processes for the production of surplus value. What we investigated are, because, the strategies of disarticulation that the bourgeoisie utilizes, under the mantle of subsidies conceptual and interventive of its management of work processes and the sieve of class struggles, to obstruct the union of workers; hamper the movements proletarians. Managerial strategies that intentionally or unintentionally, instill in the social relations of production means to produce and reproduce, activate and reactivate conditions of incitement of individualism and competition between the workers themselves. We shall see, thus, by analyzing means, centrally, from some of the fundamentals of disarticulation in the managerial strategies bourgeois and some of the fundamental strategies of management bourgeois hegemonized with the restructuring productive of 1970, that the disarticulation, and also the demobilization, is a concrete condition, is an objective condition, that is beyond a question that can be "solved" only by enlightenment cognitive, only by formation criticism intellectual. In everyday of the work spaces permeated by managerial strategies bourgeois there elements, then, operating as a material force putting difficulties important for the articulation of the workers, the solidarity of the proletariat; elements that constitute obstacle significant to an awareness of class and belonging; elements act in favor of the atomization of the worker - even if engenders, in the same process, as a contradiction, potentiality of resistance and fight the forces of labor
Resumo:
A discussão a respeito de perspectivas críticas no cenário da Educação Física é relativamente recente. Nesse sentido, nos propusemos refletir sobre a ginástica rítmica no âmbito escolar a partir de uma visão crítica, tendo como alicerce teórico-metodológico as abordagens crítico-emancipatória (KUNZ, 2001) e crítico-superadora (COLETIVO DE AUTORES, 1992), bem como os Parâmetros Curriculares Nacionais de Educação Física (BRASIL, 2001). Delimitamos nosso universo de estudo perpassando, historicamente, dos Movimentos ginásticos europeus ao contexto olímpico mundial para então, situar a entrada da ginástica rítmica no Brasil e sua inserção na escola e por fim, apontar e refletir perspectivas críticas do ensino da ginástica rítmica como conteúdo das aulas de Educação Física
Resumo:
The diffusive epidemic process (PED) is a nonequilibrium stochastic model which, exhibits a phase trnasition to an absorbing state. In the model, healthy (A) and sick (B) individuals diffuse on a lattice with diffusion constants DA and DB, respectively. According to a Wilson renormalization calculation, the system presents a first-order phase transition, for the case DA > DB. Several researches performed simulation works for test this is conjecture, but it was not possible to observe this first-order phase transition. The explanation given was that we needed to perform simulation to higher dimensions. In this work had the motivation to investigate the critical behavior of a diffusive epidemic propagation with Lévy interaction(PEDL), in one-dimension. The Lévy distribution has the interaction of diffusion of all sizes taking the one-dimensional system for a higher-dimensional. We try to explain this is controversy that remains unresolved, for the case DA > DB. For this work, we use the Monte Carlo Method with resuscitation. This is method is to add a sick individual in the system when the order parameter (sick density) go to zero. We apply a finite size scalling for estimates the critical point and the exponent critical =, e z, for the case DA > DB
Resumo:
The distribution and mobilization of fluid in a porous medium depend on the capillary, gravity, and viscous forces. In oil field, the processes of enhanced oil recovery involve change and importance of these forces to increase the oil recovery factor. In the case of gas assisted gravity drainage (GAGD) process is important to understand the physical mechanisms to mobilize oil through the interaction of these forces. For this reason, several authors have developed physical models in laboratory and core floods of GAGD to study the performance of these forces through dimensionless groups. These models showed conclusive results. However, numerical simulation models have not been used for this type of study. Therefore, the objective of this work is to study the performance of capillary, viscous and gravity forces on GAGD process and its influence on the oil recovery factor through a 2D numerical simulation model. To analyze the interplay of these forces, dimensionless groups reported in the literature have been used such as Capillary Number (Nc), Bond number (Nb) and Gravity Number (Ng). This was done to determine the effectiveness of each force related to the other one. A comparison of the results obtained from the numerical simulation was also carried out with the results reported in the literature. The results showed that before breakthrough time, the lower is the injection flow rate, oil recovery is increased by capillary force, and after breakthrough time, the higher is the injection flow rate, oil recovery is increased by gravity force. A good relationship was found between the results obtained in this research with those published in the literature. The simulation results indicated that before the gas breakthrough, higher oil recoveries were obtained at lower Nc and Nb and, after the gas breakthrough, higher oil recoveries were obtained at lower Ng. The numerical models are consistent with the reported results in the literature
Resumo:
In this work we have investigated some aspects of the two-dimensional flow of a viscous Newtonian fluid through a disordered porous medium modeled by a random fractal system similar to the Sierpinski carpet. This fractal is formed by obstacles of various sizes, whose distribution function follows a power law. They are randomly disposed in a rectangular channel. The velocity field and other details of fluid dynamics are obtained by solving numerically of the Navier-Stokes and continuity equations at the pore level, where occurs actually the flow of fluids in porous media. The results of numerical simulations allowed us to analyze the distribution of shear stresses developed in the solid-fluid interfaces, and find algebraic relations between the viscous forces or of friction with the geometric parameters of the model, including its fractal dimension. Based on the numerical results, we proposed scaling relations involving the relevant parameters of the phenomenon, allowing quantifying the fractions of these forces with respect to size classes of obstacles. Finally, it was also possible to make inferences about the fluctuations in the form of the distribution of viscous stresses developed on the surface of obstacles.