Simulation of Chua's Circuit by Means of Interval Analysis

The Chua's circuit is a paradigm for nonlinear scientific studies. It is usually simulated by means of numerical methods under IEEE 754-2008 standard. Although the error propagation problem is well known, little attention has been given to the relationship between this error and inequalities presented in Chua's circuit model. Taking the average of round mode towards $+\infty$ and $-\infty$, we showed a qualitative change on the dynamics of Chua's circuit.Comment: 6th International Conference on Nonlinear Science and Complexity - S\~ao Jos\'e dos Campos, 2016, p. 1-

A model-driven approach for mobile business information systems applications

Context: Mobile BIS apps demand is increasing, with shorter time-to-market requirements, but their production faces problems, such as handling business rules concurrently, multiple platforms, localization and extensibility. Objective: Propose a generative approach for mobile BIS apps that will mitigate the identified problems. Method: We adopted the Design Science Research methodology, that helps gaining problem understanding, identifying systemically appropriate solutions, and in evaluating innovative solutions. Results: We identified the problem and its motivation, defined the objectives for a solution, designed and developed a prototype generative tool for BIS apps, demonstrated its usage and evaluated how well it mitigates a subset of the identified problems in an observational study. Limitations: Several issues are pending such as distributed business rules enforcement and the formalization of the required transformations from the PIM to several platform-specific models (PSMs). Conclusion: We intend to contribute for reducing BIS apps time-to-market, while improving the maintainability of those apps.info:eu-repo/semantics/acceptedVersio

Scaling Behavior of Driven Interfaces Above the Depinning Transition

We study the depinning transition for models representative of each of the two universality classes of interface roughening with quenched disorder. For one of the universality classes, the roughness exponent changes value at the transition, while the dynamical exponent remains unchanged. We also find that the prefactor of the width scales with the driving force. We propose several scaling relations connecting the values of the exponents on both sides of the transition, and discuss some experimental results in light of these findings.Comment: Revtex 3.0, 4 pages in PRL format + 5 figures (available at ftp://jhilad.bu.edu/pub/abbhhss/ma-figures.tar.Z ) submitted to Phys Rev Let

Coherent pressure structures in turbulent channel flow

Most of the studies on pressure fluctuations in wall-bounded turbulent flows aim at obtaining statistics as power spectra and scaling laws, especially at the walls. In the present study we study energetic coherent pressure structures of turbulent channel flows, aiming at a characterization of dominant coherent structures throughout the channel. Coherent structures are detected using spectral proper orthogonal decomposition (SPOD) and modeled using resolvent analysis, similar to related works dealing with velocity fluctuations, but using pressure fluctuations as the output of interest. The resolvent operator was considered with and without the Cess eddy viscosity model. Direct numerical simulations (DNSs) of incompressible turbulent channel flows at friction Reynolds numbers of approximately 180 and 550 were employed as databases. Three representative dominant structures emerged from a preliminary spectral analysis: near-wall, large-scale and spanwise-coherent structures. For frequency-wavenumber combinations corresponding to these three representative structures, SPOD results show a strong dominance of the leading mode, highlighting low-rank behavior of pressure fluctuations. The leading resolvent mode closely agrees with the first SPOD mode, providing support to studies that showed better performance of resolvent-based estimators when predicting pressure fluctuations compared to velocity fluctuations. The dominant mechanisms of the analyzed modes are seen to be the generation of quasi-streamwise vortices with pressure fluctuations appearing close to vortex centers. A study on the individual contributions of the nonlinear terms (treated as forcing in resolvent analysis) to the pressure output reveals that each forcing component plays a constructive role to the input-output formulation, which also helps understanding the weaker role of forcing color in driving pressure fluctuations.Comment: 24 pages, 23 figure

On fermionic tilde conjugation rules and thermal bosonization. Hot and cold thermofields

A generalization of Ojima tilde conjugation rules is suggested, which reveals the coherent state properties of thermal vacuum state and is useful for the thermofield bosonization. The notion of hot and cold thermofields is introduced to distinguish different thermofield representations giving the correct normal form of thermofield solution for finite temperature Thirring model with correct renormalization and anticommutation properties.Comment: 13 page

Autoficção em Borderline, de Marie-Sissi Labrèche

O objetivo desta pesquisa é analisar o romance Borderline (2003), da escritora quebequense Marie-Sissi Labrèche, no campo da escrita de si, sob o prisma da autoficção, termo registrado pelo crítico e professor francês Serge Doubrovsky em Fils (1977). Este estudo visa averiguar, além da coincidência onomástica entre o nome da autora, da narradora e da personagem, a possibilidade de um jogo em que Labrèche cria um outro eu, capaz de fornecer supostas referências a traços autobiográficos mesclados a uma matéria ficcional. A pesquisa, portanto, consiste na investigação da relação entre o transtorno borderline e a estrutura do texto, examinando se o tema escolhe sua forma ideal de expressão, se a autora se faz valer dessa estrutura como sendo decisiva para inspirar a pensar esse transtorno psicológico. Ainda que a matriz teórica da autoficção seja francesa, não são muitas as publicações e trabalhos acadêmicos sobre esse efeito de leitura nas obras contemporâneas de autoras quebequenses. O corpus a ser analisado é Borderline. No que tange à teoria, serão utilizados os estudos acerca da perspectiva teórica da autoficção, por meio da contribuição de alguns teóricos, como Evando Nascimento e Leonor Arfuch. Palavras-chave: Autoficção. Borderline. Marie-Sissi Labrèche. Quebequense

Driven interfaces in disordered media: determination of universality classes from experimental data

While there have been important theoretical advances in understanding the universality classes of interfaces moving in porous media, the developed tools cannot be directly applied to experiments. Here we introduce a method that can identify the universality class from snapshots of the interface profile. We test the method on discrete models whose universality class is well known, and use it to identify the universality class of interfaces obtained in experiments on fluid flow in porous media.Comment: 4 pages, 5 figure

Statistical Properties of Business Firms Structure and Growth

We analyze a database comprising quarterly sales of 55624 pharmaceutical products commercialized by 3939 pharmaceutical firms in the period 1992--2001. We study the probability density function (PDF) of growth in firms and product sales and find that the width of the PDF of growth decays with the sales as a power law with exponent $\beta = 0.20 \pm 0.01$. We also find that the average sales of products scales with the firm sales as a power law with exponent $\alpha = 0.57 \pm 0.02$. And that the average number products of a firm scales with the firm sales as a power law with exponent $\gamma = 0.42 \pm 0.02$. We compare these findings with the predictions of models proposed till date on growth of business firms