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Search Results: 1 - 10 of 22490 matches for " Roberto Righi "
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Sulla traduzione macedone dell’Evgenij Onegin
Roberto Righi
Studi Slavistici , 2006,
Abstract: The Translation of Evgenij Onegin into Macedonian The Author analyses G. Stalev ‘s translation of Pu kin’s Onegin into Macedonian. This work is of fundamental importance in the formation of modern literary Macedonian language and testifies to its poetic and expressive possibilities. The decision to maintain the iambic verse of the original, caused Stalev several difficulties, due mainly to the difference in accent in Russian and Macedonian. The Author describes the techniques Stalev used to overcome the challenges offered by the Russian poetic text and the strategies that allowed the Macedonian poet to make an excellent translation. Forty years on, it is still a first-class example of the integration of Pu kin’s masterpiece into the linguistic and literary context of Macedonian culture.
Fluxo de seiva pelo método do balan?o de calor: base teórica, qualidade das medidas e aspectos práticos
Marin, Fábio Ricardo;Ribeiro, Rafael Vasconcelos;Angelocci, Luiz Roberto;Righi, Evandro Zanini;
Bragantia , 2008, DOI: 10.1590/S0006-87052008000100001
Abstract: the stem heat balance method has become an important technique in plant physiology, agrometeorology and irrigation science. its application has increased in the last years due to the development of less expensive automatic data acquisition systems that are widespread. important advances in several research areas have been reached by quantifying the water consumption by isolated plants in different temporal scales. based on the theory of the method, this review aims to present and discuss the procedures of installation and maintenance, and data analysis and processing, giving elements to improve the user's criticism about data quality. aspects related to the impact of environmental conditions on sensor performance are presented, as well as the practical recommendations found in literature are critically discussed. the method is a useful tool for research and experimentation, but it seems to be inadequate for use in practical conditions. difficulties involving its operational and practical aspects - installation and maintenance in field conditions - in addition to data analysis and processing are the main obstacles to the users of this technique.
Relationships of photosynthetic photon flux density, air temperature and humidity with tomato leaf diffusive conductance and temperature
Righi, Evandro Zanini;Buriol, Galileo Adeli;Angelocci, Luiz Roberto;Heldwein, Arno Bernardo;Tazzo, Ivonete Fátima;
Brazilian Archives of Biology and Technology , 2012, DOI: 10.1590/S1516-89132012000300005
Abstract: the objective was to study the leaf temperature (lt) and leaf diffusive vapor conductance (gs) responses to temperature, humidity and incident flux density of photosynthetically active photons (ppfd) of tomato plants grown without water restriction in a plastic greenhouse in santa maria, rs, brazil. the plants were grown in substrate and irrigated daily. the gs was measured using a steady-state null-balance porometer on the abaxial face of the leaves during the daytime. both leaf surfaces were measured in one day. the ppfd and lt were measured using the porometer. leaf temperature was determined using an infrared thermometer, and air temperature and humidity were measured using a thermohygrograph. the leaves on the upper layer of the plants had higher gs than the lower layer. the relationship between the gs and ppfd was different for the two layers in the plants. a consistent relationship between the gs and atmospheric water demand was observed only in the lower layer. the lt tended to be lower than the air temperature. the mean value for the gs was 2.88 times higher on the abaxial than adaxial leaf surface.
Transpiration, leaf diffusive conductance, and atmospheric water demand relationship in an irrigated acid lime orchard
Angelocci, Luiz Roberto;Marin, Fábio Ricardo;Oliveira, Ricardo Ferraz de;Righi, Evandro Zanini;
Brazilian Journal of Plant Physiology , 2004, DOI: 10.1590/S1677-04202004000100008
Abstract: leaf vapor diffusive conductance (gl) and transpiration (t) measurements in an irrigated orchard of the acid lime "tahiti" were carried out in a subtropical climatic condition in the state of s?o paulo, brazil. measurements were made using steady-state null-balance porometers and were taken throughout the day, on several occasions from february to november, 1998. during september and october, measurements were performed on exposed and shaded young and fully expanded leaves, as well as on old leaves inside the tree canopy. the old leaves showed lower values of gl and t when compared to the other groups. in the other months, measurements were taken only with exposed and shaded fully expanded leaves. the highest values of gl and t were obtained from february to april. for exposed leaves gl was higher from early morning to midday, decreasing thereafter with some oscillation in the afternoon. shaded leaves produced a pattern of increasing gl and t from 8:00-9:00 a.m. to midday, followed by a decrease when values matched those of the exposed leaves in the afternoon. in april, the first measurement in midmorning showed low gl and t values, increasing sharply in the exposed leaves until midday and then decreasing until the end of the afternoon. between may and november, gl and t decreased sharply compared to the previous months. boundary line and regression analysis were used to find the mathematical relationships between mean values of gl for the tree and photosynthetic photons flux density, temperature, and vapor pressure deficit of the air measured in the orchard. based on this analysis, the reasons for the gl and t diurnal and annual variation patterns are discussed, with emphasis on the effects of atmospheric variables upon stomatal regulation.
Transpiration, leaf diffusive conductance, and atmospheric water demand relationship in an irrigated acid lime orchard
Angelocci Luiz Roberto,Marin Fábio Ricardo,Oliveira Ricardo Ferraz de,Righi Evandro Zanini
Brazilian Journal of Plant Physiology , 2004,
Abstract: Leaf vapor diffusive conductance (gl) and transpiration (T) measurements in an irrigated orchard of the acid lime "Tahiti" were carried out in a subtropical climatic condition in the State of S o Paulo, Brazil. Measurements were made using steady-state null-balance porometers and were taken throughout the day, on several occasions from February to November, 1998. During September and October, measurements were performed on exposed and shaded young and fully expanded leaves, as well as on old leaves inside the tree canopy. The old leaves showed lower values of gl and T when compared to the other groups. In the other months, measurements were taken only with exposed and shaded fully expanded leaves. The highest values of gl and T were obtained from February to April. For exposed leaves gl was higher from early morning to midday, decreasing thereafter with some oscillation in the afternoon. Shaded leaves produced a pattern of increasing gl and T from 8:00-9:00 a.m. to midday, followed by a decrease when values matched those of the exposed leaves in the afternoon. In April, the first measurement in midmorning showed low gl and T values, increasing sharply in the exposed leaves until midday and then decreasing until the end of the afternoon. Between May and November, gl and T decreased sharply compared to the previous months. Boundary line and regression analysis were used to find the mathematical relationships between mean values of gl for the tree and photosynthetic photons flux density, temperature, and vapor pressure deficit of the air measured in the orchard. Based on this analysis, the reasons for the gl and T diurnal and annual variation patterns are discussed, with emphasis on the effects of atmospheric variables upon stomatal regulation.
Adi??es ao gênero Glossodrilus (Oligochaeta, Glossoscolecidae)
Righi, Gilberto;
Revista Brasileira de Zoologia , 1982, DOI: 10.1590/S0101-81751982000100009
Abstract: four new species of glossodrilus, g. mairaro, g. arapaco, g. oliveirae and g. tico, are described from the region between 3o - 5on and 58o - 62ow, including part of brazil, venezuela and guyana. a new occurrence is indicated for g. schubarti. the subgenus glossodrilus (tonperoge) is invalidated. a pragmatic system is presented to group the 31 species and subspecies of glossodrilus.
A Gas-Kinetic Scheme For The Simulation Of Compressible Turbulent Flows
Marcello Righi
Physics , 2013, DOI: 10.1063/1.4902750
Abstract: The kinetic theory of gases has suggested the idea of viscosity to model the effect of thermal fluctuations on the resolved flow. Supported by the assumed analogy between molecules and the eddies in a turbulent flows, the idea of an eddy viscosity has been put forward in the pioneering work by Lord Kelvin and Osborne Reynolds. In over hundred years of turbulence modeling, the numerical schemes adopted to simulate turbulent flow - with the exception of the Lattice Boltzmann methods - have never exploited this analogy in any other way. In this work, a gas-kinetic scheme is modified to simulate turbulent flow; the turbulent relaxation time is deduced from assumed turbulent quantities. The new scheme does not adopt an eddy viscosity, yet it relies even more strongly on the analogy between thermal and turbulent fluctuations, as turbulence dynamics is mathematically modeled by the Boltzmann equation. In the gas-kinetic scheme, a measure of the degree of rarefaction is introduced, as the ratio between unresolved and resolved time scales of motion. At low rarefaction, the turbulent gas-kinetic scheme deviates negligibly from a conventional Navier-Stokes scheme. However, as the degree of rarefaction increases, the kinetic effects become evident. This phenomenon is evident in the mathematical description of the turbulent stress tensor and also in numerical experiments. This study does not propose an innovative turbulence model or technique. It addresses the fact that the traditional coupling numerical scheme and turbulence modeling might improve the physical consistence of numerical simulations.
A gas-kinetic scheme for the simulation of turbulent flows
Marcello Righi
Physics , 2012, DOI: 10.1063/1.4769575
Abstract: Numerical schemes derived from gas-kinetic theory can be applied to simulations in the hydrodynamics limit, in laminar and also turbulent regimes. In the latter case, the underlying Boltzmann equation describes a distribution of eddies, in line with the concept of eddy viscosity developed by Lord Kelvin and Osborne Reynolds at the end of the nineteenth century. These schemes are physically more consistent than schemes derived from the Navier-Stokes equations, which invariably assume infinite collisions between gas particles (or interactions between eddies) in the calculation of advective fluxes. In fact, in continuum regime too, the local Knudsen number can exceed the value 0.001 in shock layers, where gas-kinetic schemes outperform Navier-Stokes schemes, as is well known. Simulation of turbulent flows benefit from the application of gas-kinetic schemes, as the turbulent Knudsen number (the ratio between the eddies' mean free path and the mean flow scale) can locally reach values well in excess of 0.001, not only in shock layers. This study has investigated a few cases of shock - boundary layer interaction comparing a gas-kinetic scheme and a Navier-Stokes one, both with a standard k-\omega turbulence model. Whereas the results obtained from the Navier-Stokes scheme are affected by the limitations of eddy viscosity two-equation models, the gas-kinetic scheme has performed much better without making any further assumption on the turbulent structures.
A Modified Gas-Kinetic Scheme for Turbulent Flow
Marcello Righi
Physics , 2013,
Abstract: By analogy with the kinetic theory of gases, most turbulence modeling strate- gies rely on an eddy viscosity to model the unresolved turbulent fluctuations. How- ever, the ratio of unresolved to resolved scales - very much like a degree of rarefaction - is not taken into account by the popular conventional schemes, based on the Navier- Stokes equations. This paper investigates the simulation of turbulent flow with a gas- kinetic scheme. In so doing, the modeling of turbulence becomes part of the numerical scheme: the degree of rarefaction is automatically taken into account; the turbulent stress tensor is not constrained into a linear relation with the strain rate. Instead it is modeled on the basis of the analogy between particles and eddies, without any as- sumptions on the type of turbulence or flow class. The implementation of a turbulent gas-kinetic scheme into a finite-volume solver is put forward, with turbulent kinetic energy and dissipation supplied by an allied turbulence model. A number of flow cases, challenging for conventional RANS methods, are investigated; results show that the shock-turbulent boundary layer is captured in a much more convincing way by the gas-kinetic scheme.
Enumeration of ad-nilpotent ideals of parabolic subalgebras for exceptional types
Celine Righi
Mathematics , 2008,
Abstract: Using GAP4, we determine the number of ad-nilpotent and abelian ideals of a parabolic subalgebra of a simple Lie algebra of exceptional types E, F or G.
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