Conservative upwind difference schemes for the Euler equations for real gas flows in a duct

In a recent paper [P. Glaister, Conservative upwind difference schemes for compressible flows in a Duct, Comput. Math. Appl. 56 (2008) 1787–1796] numerical schemes based on a conservative linearisation are presented for the Euler equations governing compressible flows of an ideal gas in a duct of variable cross-section, and in [P. Glaister, Conservative upwind difference schemes for compressible flows of a real gas, Comput. Math. Appl. 48 (2004) 469–480] schemes based on this philosophy are presented for real gas flows with slab symmetry. In this paper we seek to extend these ideas to encompass compressible flows of real gases in a duct. This will incorporate the handling of additional terms arising out of the variable geometry and the non-ideal nature of the gas.

Linear-wavelet models applied to the identification of a two-link manipulator

This paper shows that a wavelet network and a linear term can be advantageously combined for the purpose of non linear system identification. The theoretical foundation of this approach is laid by proving that radial wavelets are orthogonal to linear functions. A constructive procedure for building such nonlinear regression structures, termed linear-wavelet models, is described. For illustration, sim ulation data are used to identify a model for a two-link robotic manipulator. The results show that the introduction of wavelets does improve the prediction ability of a linear model.

Adaptive modelling with tunable RBF network using multi-innovation RLS algorithm assisted by swarm intelligence

In this paper, we propose a new on-line learning algorithm for the non-linear system identification: the swarm intelligence aided multi-innovation recursive least squares (SI-MRLS) algorithm. The SI-MRLS algorithm applies the particle swarm optimization (PSO) to construct a flexible radial basis function (RBF) model so that both the model structure and output weights can be adapted. By replacing an insignificant RBF node with a new one based on the increment of error variance criterion at every iteration, the model remains at a limited size. The multi-innovation RLS algorithm is used to update the RBF output weights which are known to have better accuracy than the classic RLS. The proposed method can produces a parsimonious model with good performance. Simulation result are also shown to verify the SI-MRLS algorithm.

Playing Kant at the Court of King Arthur

This article contrasts the sense in which those whom Bernard Williams called ‘political realists’ and John Rawls are committed to the idea that political philosophy has to be distinctively political. Distinguishing the realist critique of political moralism from debates over ideal and non-ideal theory, it is argued that Rawls is more realist than many realists realise, and that realists can learn more about how to make a distinctively political vision of how our life together should be organised from his theorising, although it also points to a worrying tendency among Rawlsians to reach for inappropriately moralised arguments. G. A. Cohen’s advocacy of socialism and the second season of HBO’s The Wire are used as examples to illustrate these points.

Black-box decomposition approach for computational hemodynamics: One-dimensional models

Increasing efforts exist in integrating different levels of detail in models of the cardiovascular system. For instance, one-dimensional representations are employed to model the systemic circulation. In this context, effective and black-box-type decomposition strategies for one-dimensional networks are needed, so as to: (i) employ domain decomposition strategies for large systemic models (1D-1D coupling) and (ii) provide the conceptual basis for dimensionally-heterogeneous representations (1D-3D coupling, among various possibilities). The strategy proposed in this article works for both of these two scenarios, though the several applications shown to illustrate its performance focus on the 1D-1D coupling case. A one-dimensional network is decomposed in such a way that each coupling point connects two (and not more) of the sub-networks. At each of the M connection points two unknowns are defined: the flow rate and pressure. These 2M unknowns are determined by 2M equations, since each sub-network provides one (non-linear) equation per coupling point. It is shown how to build the 2M x 2M non-linear system with arbitrary and independent choice of boundary conditions for each of the sub-networks. The idea is then to solve this non-linear system until convergence, which guarantees strong coupling of the complete network. In other words, if the non-linear solver converges at each time step, the solution coincides with what would be obtained by monolithically modeling the whole network. The decomposition thus imposes no stability restriction on the choice of the time step size. Effective iterative strategies for the non-linear system that preserve the black-box character of the decomposition are then explored. Several variants of matrix-free Broyden`s and Newton-GMRES algorithms are assessed as numerical solvers by comparing their performance on sub-critical wave propagation problems which range from academic test cases to realistic cardiovascular applications. A specific variant of Broyden`s algorithm is identified and recommended on the basis of its computer cost and reliability. (C) 2010 Elsevier B.V. All rights reserved.

Informal sanctions and conditional cooperation: : A natural experiment on voluntary contributions to a public good.

In a natural experiment, this paper studies the impact of an informal sanctioning mechanism on individuals’ voluntary contribution to a public good. Cross-country skiers’ actual cash contributions in two ski resorts, one with and one without an informal sanctioning system, are used. I find the contributing share to be higher in the informal sanctioning system (79 percent) than in the non-sanctioning system (36 percent). Previous studies in one-shot public good situations have found an increasing conditional contribution (CC) function, i.e. the relationship between expected average contributions of other group members and the individual’s own contribution. In contrast, the present results suggest that the CC-function in the non-sanctioning system is non-increasing at high perceived levels of others’ contribution. This relationship deserves further testing in lab.

Critical intellectual resources for praxis in physical education teacher education : the limits to rationality

This study focuses on the way four student-teachers engage with critical social discourses in a year-long physical education unit. The student-teachers were encouraged to examine and (re)construct their pedagogy through their interactions with critical discourses. Drawing on their personal theories and actions, the study examines the extent to which critical intellectual resources can provide pedagogical frames of reference that are 'practical and non-ideal'. Using a critical ethnographic methodology the students' interactions with critical social discourses are diagnosed across three levels. The first level is the case study presentations of each student's engagement with the critical intellectual resources and the extent to which they were able to understand and implement them. The second level involves an interpretation of the individual cases that is informed by Brian Fay's (1987) metatheoretical reconstruction of the critical social sciences. In the third stage of diagnosis the study focuses on retheorising critical aspirations for praxis pedagogy in physical education. Critical scholars within the physical education arena argue that critical praxis represents a pedagogy based on a 'world view' of the potential for agents to engage in a rational reordering of their qualitative existence. The essence of their claim is that critical discourses have the potential to facilitate a mode of praxis through which physical education teachers might better recognise, understand, critique and transform their values and practices. However, there is broad recognition that the translation of social-critical discourses into a pedagogic context is highly problematic. Interpretation of the study is provided by Fay's (1987) 'limits to change' thesis which recognises that critical aspirations must ultimately be adopted and implemented by real people in real settings. As a diagnostic frame of reference, Fay insists that a 'complete' critical theory [of physical education] be simultaneously scientific, critical, practical and non-ideal. In seeking to temper the "e; over-rationalistic"e; tendency of the critical project he recognises the historical, embedded, embodied and traditional nature of human existence Criticisms of critical theories of education traverse a number of philosophic perspectives. Recent post-structural criticisms of truth regimes, knowledge-power differentials, rationality and agency have seriously destabilised modernist justifications of the critical agenda. Critical theories of physical education have not been absolved of such criticism. A prominent element of this study is its promotion of a dialectical relationship between agency and structure to extend critical conceptualisations of physical education pedagogy. Through the mediation of structural determinism and self-determination this research proffers a means of practically advancing a critical praxis in physical education. The conclusion of this thesis outlines some broad recommendations pertaining to the introduction of social critical discourses in physical education teacher education.

New blind source estimation methods based on constant modulus criterion

This thesis presents two novel algorithms for blind chancel equalization (BCE) and blind source separation (BSS). Beside these, a general framework for global convergent analysis is proposed. Finally, the open problem of equalising a non-irreducible system is answered by the algorithm proposed in this thesis.

Shear-enhanced solution precipitation : a simple process to produce short polymeric nanofibers

The growing interest in polymeric nanofibers has been increasing the push for the development of simple and efficient nanofiber-preparation techniques. We herein describe how a conventional solution process is readapted to suit the needs for fast and efficient production of short polymeric nanofibers. Poly(ethylene-co-acrylic acid) (PEAA), a semi-crystalline polymer, was used as model. When a PEAA solution was injected into an alcoholic non-solvent while simultaneously applying high shear to the non-solvent system, PEAA nanofibers were obtained with average diameter as thin as 113 nm and length as short as 4.5 _m. The fiber diameter and length were also adjustable by varying the operating parameters. This one-step technique advances the currently available nanofabrication tools by adjusting a widely accepted concept to the nano-scale. It may constitute a viable method for large-scale production of short polymeric nanofibers.

How did this snail get here? Several dispersal vectors inferred for an aquatic invasive species

1. How species reach and persist in isolated habitats remains an open question in many cases, especially for rapidly spreading invasive species. This is particularly true for temporary freshwater ponds, which can be remote and may dry out annually, but may still harbour high biodiversity. Persistence in such habitats depends on recurrent colonisation or species survival capacity, and ponds therefore provide an ideal system to investigate dispersal and connectivity. 2. Here, we test the hypothesis that the wide distributions and invasive potential of aquatic snails is due to their ability to exploit several dispersal vectors in different landscapes. We explored the population structure of Physa acuta (recent synonyms: Haitia acuta, Physella acuta, Pulmonata: Gastropoda), an invasive aquatic snail originating from North America, but established in temporary ponds in Doñana National Park, southern Spain. In this area, snails face land barriers when attempting to colonise other suitable habitat. 3. Genetic analyses using six microsatellite loci from 271 snails in 21 sites indicated that (i) geographically and hydrologically isolated snail populations in the park were genetically similar to a large snail population in rice fields more than 15 km away; (ii) these isolated ponds showed an isolation-by-distance pattern. This pattern broke down, however, for those ponds visited frequently by large mammals such as cattle, deer and wild boar; (iii) snail populations were panmictic in flooded and hydrologically connected rice fields. 4. These results support the notion that aquatic snails disperse readily by direct water connections in the flooded rice fields, can be carried by waterbirds flying between the rice fields and the park and may disperse between ponds within the park by attaching to large mammals. 5. The potential for aquatic snails such as Physa acuta to exploit several dispersal vectors may contribute to their wide distribution on various continents and their success as invasive species. We suggest that the interaction between different dispersal vectors, their relation to specific habitats and consequences at different geographic scales should be considered both when attempting to control invasive freshwater species and when protecting endangered species.

As dificuldades da reforma tributária como um jogo de elites na visão das elites pernambucanas

O presente texto está focado na temática da Reforma Tributária e, em particular, na sua dificuldade em ser aprovada pelo Congresso Nacional. Sendo o Sistema Tributário a base da manutenção do federalismo, já que sem a partilha das receitas tributárias entre os entes federados não há como assegurar sua independência financeira e, portanto, também sua autonomia, o contexto federativo se apresenta como um dificultador. A Reforma, além de tratar de aproximar o atual Sistema Tributário de um sistema ideal, tem que procurar manter uma autonomia mínima dos entes para que o Estado Federal – cláusula pétrea de nossa Constituição Federal - não se converta em Unitário. Nesse panorama, a relação entre o Executivo Federal, os Executivos Estaduais e o Congresso Nacional, no que tange à aprovação de assuntos ligados à agenda da Reforma Tributária, se reveste de fundamental importância para o entendimento dos obstáculos que têm levado à paralisação os principais projetos a ela ligados. Importante, também, se afigura o entendimento do jogo entre as elites que ocorre dentro e fora do Congresso Nacional, resultando substanciais alterações nessas propostas. Nesse sentido, a teoria das escolhas racionais se mostra uma ferramenta adequada para ajudar nessa compreensão. Para se alcançar o objetivo proposto - levantar os obstáculos que têm impedido o avanço de projetos que visem promover ampla reforma no Sistema Tributário brasileiro -, foram realizadas 28 entrevistas que tiveram com requisitos básicos para a seleção dos sujeitos: o de estarem exercendo suas atividades no Estado de Pernambuco; e de terem participado direta ou indiretamente em processos de Reformas Tributárias amplas, em particular, da proposta que foi apresentada em 2008 por meio da PEC 233/08. Foram entrevistados Ex-ministros de Estado, Ex-governadores, Secretários e Ex- Secretários das Receitas das três esferas de Poder, Deputados Federais, líderes empresariais, líderes de órgãos e entidades de classe, advogados tributaristas e agentes do fisco estadual. Os resultados obtidos sugerem que, embora existam diversos obstáculos de difícil superação e que devem ser esgotados em mesas de negociação antes de a proposta ser remetida ao Congresso Nacional, o conflito distributivo entre os entes federados se apresenta como o principal problema a ser observado. A sua presença parece ter a capacidade de romper o tecido partidário e dissolver as coalizões de apoio e de oposição ao Governo, repercutindo sobre o eixo da negociação que, para processos dessa natureza, passa a ser entre os Executivos Federal e Estaduais e não mais entre o Executivo Federal e sua coalizão de apoio, como normalmente ocorre.

Memorial de formação: um dispositivo de pesquisa ação - formação

La recherche prend comme point de départ la dimension formative du mémoire de formation, considerée comme constitutive de l´écriture de soi, et cherche à problématiser cette dimension au tour du questionnement suivant: Comment le mémoire de formation devient-il un instrument de recherche-action-formation? Les analyses s´appuient sur les principes théoriques du paradigme anthropoformateur, proposé par Pineau (2005), les études réalisées par Passeggi (2006ª, 2006b, 2007, 2008ª, 2008b) sur les mémoires, les travaux de recherche de Nóvoa (1988, 1995), de Josso (2004), de Souza (2006) et de Fontana (2000), qui conçoivent la formação du point de vue de l´ apprenant. L´univers de la recherche s´est circonscrit à la situation de formation des éducateurs de la zone rurale, étudiants en Pédagogie dans le PROFORMAÇÃO (CAMEAM), à l´Univeristé de l´Etat du Rio Grande du Nord (UERN), pendant le second semestre de 2005. La recherche a croisé diférents types de démarche pour recueillir les données empiriques: l´observation du processus d´élaboration des mémoires; un questionnaire; des entretiens informels avec les enseignants en formation et avec les formateurs; et 09 mémoires, écrits par les participants de la recherche. Les analyses des données empiriques montrent que l´écriture des mémoires, en tant que démarche de recherche-action-formation, révelent que la dimension formative se dédouble en d´autres dimensions: etnosociologique, heuristique, herméneutique, social et afective, autopoiétique et politique. Dans la quête de soi (recherche), mise en oeuvre dans et par l´écriture (action), chaque narrateur construit de nouveaux sens à la vie et (re)signifient les représentations de soi (formation). Les résultats confirment la richesse et les potentialités du mémoire, même dans des conditions non ideal, ce qui permet d´affirmer as valeur travail académique important dans la formation des enseignants

Equalização neural aplicada a sistemas com modulação bidimensional em fibra óptica

Nowadays, optic fiber is one of the most used communication methods, mainly due to the fact that the data transmission rates of those systems exceed all of the other means of digital communication. Despite the great advantage, there are problems that prevent full utilization of the optical channel: by increasing the transmission speed and the distances involved, the data is subjected to non-linear inter symbolic interference caused by the dispersion phenomena in the fiber. Adaptive equalizers can be used to solve this problem, they compensate non-ideal responses of the channel in order to restore the signal that was transmitted. This work proposes an equalizer based on artificial neural networks and evaluates its performance in optical communication systems. The proposal is validated through a simulated optic channel and the comparison with other adaptive equalization techniques

Determinação de dados de equilíbrio de fases para sistemas aquosos com eletrólitos

In the present work are established initially the fundamental relationships of thermodynamics that govern the equilibrium between phases, the models used for the description of the behavior non ideal of the liquid and vapor phases in conditions of low pressures. This work seeks the determination of vapor-liquid equilibrium (VLE) data for a series of multicomponents mixtures of saturated aliphatic hydrocarbons, prepared synthetically starting from substances with analytical degree and the development of a new dynamic cell with circulation of the vapor phase. The apparatus and experimental procedures developed are described and applied for the determination of VLE data. VLE isobarics data were obtained through a Fischer s ebulliometer of circulation of both phases, for the systems pentane + dodecane, heptane + dodecane and decane + dodecane. Using the two new dynamic cells especially projected, of easy operation and low cost, with circulation of the vapor phase, data for the systems heptane + decane + dodecane, acetone + water, tween 20 + dodecane, phenol + water and distillation curves of a gasoline without addictive were measured. Compositions of the equilibrium phases were found by densimetry, chromatography, and total organic carbon analyzer. Calibration curves of density versus composition were prepared from synthetic mixtures and the behavior excess volumes were evaluated. The VLE data obtained experimentally for the hydrocarbon and aqueous systems were submitted to the test of thermodynamic consistency, as well as the obtained from the literature data for another binary systems, mainly in the bank DDB (Dortmund Data Bank), where the Gibbs-Duhem equation is used obtaining a satisfactory data base. The results of the thermodynamic consistency tests for the binary and ternary systems were evaluated in terms of deviations for applications such as model development. Later, those groups of data (tested and approved) were used in the KijPoly program for the determination of the binary kij parameters of the cubic equations of state original Peng-Robinson and with the expanded alpha function. These obtained parameters can be applied for simulation of the reservoirs petroleum conditions and of the several distillation processes found in the petrochemistry industry, through simulators. The two designed dynamic cells used equipments of national technology for the determination of VLE data were well succeed, demonstrating efficiency and low cost. Multicomponents systems, mixtures of components of different molecular weights and also diluted solutions may be studied in these developed VLE cells

Determinação de Dados de Equilíbrio Líquido-Vapor para Sistemas Hidrocarbonetos e Desenvolvimento de uma Nova Célula Dinâmica

In the present work are established initially the fundamental relationships of thermodynamics that govern the equilibrium between phases, the models used for the description of the behavior non ideal of the liquid and vapor phases in conditions of low pressures. This work seeks the determination of vapor-liquid equilibrium (VLE) data for a series of multicomponents mixtures of saturated aliphatic hydrocarbons, prepared synthetically starting from substances with analytical degree and the development of a new dynamic cell with circulation of the vapor phase. The apparatus and experimental procedures developed are described and applied for the determination of VLE data. VLE isobarics data were obtained through a Fischer's ebulliometer of circulation of both phases, for the systems pentane + dodecane, heptane + dodecane and decane + dodecane. Using the two new dynamic cells especially projected, of easy operation and low cost, with circulation of the vapor phase, data for the systems heptane + decane + dodecane, acetone + water, tween 20 + dodecane, phenol + water and distillation curves of a gasoline without addictive were measured. Compositions of the equilibrium phases were found by densimetry, chromatography, and total organic carbon analyzer. Calibration curves of density versus composition were prepared from synthetic mixtures and the behavior excess volumes were evaluated. The VLE data obtained experimentally for the hydrocarbon and aqueous systems were submitted to the test of thermodynamic consistency, as well as the obtained from the literature data for another binary systems, mainly in the bank DDB (Dortmund Data Bank), where the Gibbs-Duhem equation is used obtaining a satisfactory data base. The results of the thermodynamic consistency tests for the binary and ternary systems were evaluated in terms of deviations for applications such as model development. Later, those groups of data (tested and approved) were used in the KijPoly program for the determination of the binary kij parameters of the cubic equations of state original Peng-Robinson and with the expanded alpha function. These obtained parameters can be applied for simulation of the reservoirs petroleum conditions and of the several distillation processes found in the petrochemistry industry, through simulators. The two designed dynamic cells used equipments of national technology for the determination Humberto Neves Maia de Oliveira Tese de Doutorado PPGEQ/PRH-ANP 14/UFRN of VLE data were well succeed, demonstrating efficiency and low cost. Multicomponents systems, mixtures of components of different molecular weights and also diluted solutions may be studied in these developed VLE cells