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| Registros recuperados: 127 | |
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| Thouvenin, Benedicte; Salomon, Jean-claude. |
| In order to reproduce and investigate the marine circulation in the coastal tidal zone, and especially its three dimensional nature, it appeared interesting to develop a numerical mode! which could take account of the real bottom topography and the variations of the free surface. Navier-Stokes equations are solved in a straight forward manner, generalizing a finite difference technique already used in two-dimensional vertical models. To test the computational program, the mode! was applied to a number of flat bottom schematic basins, where we reproduced wind driven currents and tide propagation. Then we considered the particular case of a real channel and, finally, density currents associated with a salty wall. Mode) results are compared to theoretical... |
| Tipo: Text |
Palavras-chave: Modèle; Courant; Tridimensionnel; Seine; Côtier; Model; Current; Three-dimensional; Seine; Coastal. |
| Ano: 1984 |
URL: http://archimer.ifremer.fr/doc/00113/22440/20127.pdf |
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| Hammen, L. van der. |
| The present paper constitutes an introduction to taxonomic methodology. After an analysis of taxonomic practice, and a brief survey of kinds of attributes, the paper deals with observation, description, comparison, arrangement and classification, hypothesis construction, deduction, model, experiment, abstraction, and synthesis. The methodological aspects of the species-concept and of biological classification are dealt with in two final sections. |
| Tipo: Article / Letter to the editor |
Palavras-chave: Abstraction; Classification; Comparison; Deduction; Description; Experiment; Hypothesis; Methodology; Model; Observation; Species-concept; Synthesis; Systematics; Taxonomy; 42.03; 42.70. |
| Ano: 1986 |
URL: http://www.repository.naturalis.nl/record/318283 |
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| Millet, B. |
| The wind-driven flow in the closed bassin de Thau is reproduced with a two-dimensional numerical model of horizontal ciruclation using an Alternate Direction Implicit scheme. A stochastic analysis of frequencies on a yearly time scale of the velocity fields computed in the model and a spatial and stochastic treatment of the term (H2 y2), similar to an effective coefficient of horizontal dispersion by shear effect are presented. This approach will allow the delineation, in a stochastic manner, of the main structures of the circulation in the lagoon and the spatial heterogeneity of its ecohydrodynamic features. Two attempts of analogical research are presented, with sorne examples of the spatial structure in the phytoplankton biomass and the map of the... |
| Tipo: Text |
Palavras-chave: Lagune; Modèle; Circulation; Dispersion; Sédiment; Lagoon; Model; Circulation; Dispersion; Sediment. |
| Ano: 1989 |
URL: http://archimer.ifremer.fr/doc/00323/43399/43093.pdf |
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| Muller-feuga, Arnaud. |
| After a literature overview of growth models applied to intensively cultured fishes, a new one is proposed for assistance in rearing operations, with following characteristics. A simple and integratable mathematic expression simulates growth while eliminating individual weight influence. It gives way to a specific growth general definition. Temperature action mode on growth speed is simulated by substraction of two exponential functions. An automatic calculation method of thermal parameters is proposed. The torpid action of low temperatures is considered. Feeding ration influences growth through simple rules which are explicitly taken in account by mean of a two parameters function. The other growth factors, more difficult to seize, are expressed through a... |
| Tipo: Text |
Palavras-chave: Modèle; Croissance; Élevage poissons; Pisciculture; Model; Fish culture.; Growth. |
| Ano: 1990 |
URL: http://archimer.ifremer.fr/doc/00183/29428/27794.pdf |
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| Scheffer, Marten; Wageningen Agricultural University; Marten.Scheffer@wur.nl. |
| Despite the huge scientific progress of the last century, the dynamics of complex systems such as the atmosphere, human societies, and ecosystems remain difficult to understand and predict. Nonetheless, our ability to carve the future depends largely on our insight into the functioning of such complex systems. Complex systems are the focus of considerable mathematical theory. Rather than referring to any particular part of the world, such theory addresses what seems to be another world: a world of strange attractors, catastrophe folds, torus destruction, and homoclinic bifurcations. So disparate is the language and notation in this discipline that it is hard to imagine that it has any thing to do with reality as we know it. Indeed, it deals with a kind of... |
| Tipo: Peer-Reviewed Reports |
Palavras-chave: Bifurcation; Catastrophe; Chaos; Cycle; Daphnia; Fish; Macrophyte; Model; Multiple stable states; Plankton; Predation; Trophic cascade. |
| Ano: 1999 |
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| Pagand, Pascal; Blancheton, Jean-paul; Casellas, Claude. |
| Fish excretions and the transformation of nitrogen by bacteria in the nitrifying biofilter are two of the main sources of dissolved inorganic nitrogen (DIN) in fish farms that use recirculating water systems. In this study, the DIN concentration in an experimental Dicentrarchus labrax aquaculture system was calculated using empirical sub-models for fish growth, ingested food and water replacement. The specific growth rate (SGR) (% day(-1)) and the daily feeding rate (DFR) (% day(-1)) both depend on the average weight, W (g), of the fish: Y = aW(b), where Y may be SGR or DFR, and a and b are empirical constants. The DIN discharge rate, Gamma(N) (% of ingested nitrogen), in the experimental aquaculture system was expressed as a function of increasing... |
| Tipo: Text |
Palavras-chave: Recirculating water system; Nitrogen production; Model; Fish farm effluent; European sea bass; Dissolved inorganic nitrogen. |
| Ano: 2000 |
URL: http://archimer.ifremer.fr/doc/2000/publication-514.pdf |
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| Ortiz De Zarate, Victoria; Bertignac, Michel. |
| In this study, an attempt is made to estimate natural mortality rate for North Atlantic albacore. We implement a spatially aggregated tag-attrition model to analyse the results of an albacore tagging experiment conducted in the Bay of Biscay from 1988 to 1991. The model predicts probabilities of the possible fates of tagged fish and the tags that they carry. The model includes several parameters consisting of catchabilities by fleets involved in recaptures and a combination of natural mortality plus emigration from the study area. Model fitting is carried out by finding the maximum of a multinomial likelihood function. Effect of reporting rate values on the estimations are evaluated and several hypothesis on the pre-mixing period of the tagged fish... |
| Tipo: Text |
Palavras-chave: Bay of Biscay; Attrition rate; Model; Natural mortality estimation; Albacore. |
| Ano: 2001 |
URL: http://archimer.ifremer.fr/doc/2001/publication-977.pdf |
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| Meysman, F.. |
| Within the natural sciences, it has long been recognized that biological activity can modify the texture, structure and composition of surface sediments. Darwin (1881) already examined the stirring of soils by burrowing earthworms and made detailed observations on how these organisms affect soil processes. A similar phenomenon can be observed in aquatic sediments, which are inhabited by a diverse biological community, supported by the flux of organic matter and oxygen from the overlying water column. Surface sediments of oceans, estuaries, lakes and rivers are highly active biogeochemical environments and an effective way to generate insight in the complexity of the interactions is by means of so-called general early diagenetic models (e.g. Soetaert et al,... |
| Tipo: Info:eu-repo/semantics/doctoralThesis |
Palavras-chave: Chemistry; Ecology; Hydrology; Model; Sediment; Water. |
| Ano: 2001 |
URL: http://www.vliz.be/nl/open-marien-archief?module=ref&refid=8063 |
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| Sedjo, Roger A.; Sohngen, Brent; Mendelsohn, Robert. |
| This study develops cumulative carbon 'supply curves' for global forests utilizing an dynamic timber supply model for sequestration of forest carbon. Because the period of concern is the next century, and particular time points within that century, the curves are not traditional Marshallian supply curves or steady-state supply curves. Rather, the focus is on cumulative carbon cost curves (quasi-supply curves) at various points in time over the next 100 years. The research estimates a number of long-term, cumulative, carbon quasi-supply curves under different price scenarios and for different time periods. The curves trace out the relationship between an intertemporal price path for carbon, as given by carbon shadow prices, and the cumulative carbon... |
| Tipo: Working or Discussion Paper |
Palavras-chave: Carbon supply curves; Sequestration; Timber; Forests; Model; Global warming; Prices; Markets; Resource /Energy Economics and Policy; Q10; Q15; Q21; Q23; Q24. |
| Ano: 2001 |
URL: http://purl.umn.edu/10663 |
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| Registros recuperados: 127 | |
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