33 resultados para Fluctuations de courant
Resumo:
Abstract. Peat surface CO2 emission, groundwater table depth and peat temperature were monitored for two years along transects in an Acacia plantation on thick tropical peat (>4 m) in Sumatra, Indonesia. A total of 2300 emission measurements were taken at 144 locations. The autotrophic root respiration component of the CO2 emission was separated from heterotrophic emissions caused by peat oxidation in three ways: (i) by comparing CO2 emissions within and beyond the tree rooting zone, (ii) by comparing CO2 emissions with and without peat trenching (i.e. cutting any roots remaining in the peat beyond the tree rooting zone), and (iii) by comparing CO2 emissions before and after Acacia tree harvesting. On average, the contribution of root respiration to daytime CO2 emission is 21 % along transects in mature tree stands. At locations 0.5 m from trees this is up to 80 % of the total emissions, but it is negligible at locations more than 1.3 m away. This means that CO2 emission measurements well away from trees are free of any root respiration contribution and thus represent only peat oxidation emission. We find daytime mean annual CO2 emission from peat oxidation alone of 94 t ha−1 yr−1 at a mean water table depth of 0.8 m, and a minimum emission value of 80 t ha−1 yr−1 after correction for the effect of diurnal temperature fluctuations, which resulted in a 14.5 % reduction of the daytime emission. There is a positive correlation between mean long-term water table depths and peat oxidation CO2 emission. However, no such relation is found for instantaneous emission/water table depth within transects and it is clear that factors other than water table depth also affect peat oxidation and total CO2 emissions. The increase in the temperature of the surface peat due to plantation development may explain over 50 % of peat oxidation emissions.
Resumo:
The subject of my doctoral thesis is the social contextuality of Finnish theater director, Jouko Turkka's (b. 1942) educational tenure in the Theater Academy of Finland 1982 1985. Jouko Turkka announced in the opening speech of his rectorship in 1982 that Finnish society had undergone a social shift into a new cultural age, and that actors needed new facilities like capacity, flexibility, and ability for renewal in their work. My sociological research reveals that Turkka adapted cultural practices and norms of new capitalism and new liberalism, and built a performance environment for actors' educational work, a real life simulation of a new capitalist workplace. Actors educational praxis became a cultural performance, a media spectacle. Turkka's tenure became the most commented upon and discussed era in Finnish postwar theater history. The sociological method of my thesis is to compare information of sociological research literature about new capitalist work, and Turkka's educational theater work. In regard to the conceptions of legitimation, time, dynamics, knowledge, and social narrative consubstantial changes occurred simultaneously in both contexts of workplace. I adapt systems and chaos theory's concepts and modules when researching how a theatrical performance self-organizes in a complex social space and the space of Information. Ilya Prigogine's chaos theoretic concept, fluctuation, is the central social and aesthetic concept of my thesis. The chaos theoretic conception of the world was reflected in actors' pedagogy and organizational renewals: the state of far from equilibrium was the prerequisite of creativity and progress. I interpret the social and theater's aesthetical fluctuations as the cultural metaphor of new capitalism. I define the wide cultural feedback created by Turkka's tenure of educational praxis, and ideas adapted from the social context into theater education, as an autopoietic communicative process between theater education and society: as a black box, theater converted the virtual conception of the world into a concrete form of an actor's psychophysical praxis. Theater educational praxis performed socially contextual meanings referring to a subject's position in the social change of 1980s Finland. My other theoretic framework lies close to the American performance theory, with its close ties to the social sciences, and to the tradition of rhetoric and communication: theater's rhetorical utility materializes quotidian cultural practices in a theatrical performance, and helps the audience to research social situations and cultural praxis by mirroring them and creating an explanatory frame.
Resumo:
We consider a chain composed of $N$ coupled harmonic oscillators in contact with heat baths at temperature $T_\ell$ and $T_r$ at sites 1 and $N$ respectively. The oscillators are also subjected to non-momentum conserving bulk stochastic noises. These make the heat conductivity satisfy Fourier's law. Here we describe some new results about the hydrodynamical equations for typical macroscopic energy and displacement profiles, as well as their fluctuations and large deviations, in two simple models of this type.