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| Registros recuperados: 103 | |
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| Plaisant, M. |
| Empirical models already exist for ambient noise spectral density function of frequency, sea state or wind speed but they give no information on the spatial structure or coherence of the noise field which is essential as soon as array beamforming is involved. We have developed a model which computes the spatial coherence matrix of the noise field due to a continuous distribution of sources located at the sea surface, and also the noise power spectral density after classical beamforming on an equidistant hydrophones linear array. In this model, propagation effects like rays bending due to variations of index of refraction and multiple bottom and surface reflections are taken into account. Principles of the modeling are presented and results demonstrate that... |
| Tipo: Text |
Palavras-chave: Spectral analysis; Models; Wind speed; Sea surface; Surface water waves; Acoustic equipment; Sound waves; Underwater noise; Ambient noise. |
| Ano: 1990 |
URL: http://archimer.ifremer.fr/doc/1990/acte-1143.pdf |
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| Heral, Maurice. |
| In areas where oyster or mussel culture is very intensive, declines of growth rate and decreases of survival rate have occurred. For these reasons, plans have been proposed to regulate the cultivated biomasses in order to fit the carrying capacity of the different ecosystems (Heral et al 1990; Heral, 1991). In areas where new aquaculture of molluscs is beginning, oyster or mussel farmers need to know how large the extension of the culture could be and what the maximal densities should be in order to obtain the maximum economic benefit. Furthermore, as mollusc cultures are developed in coastal areas, they are very susceptible to changes in environmental conditions that can modify trophic relationships, or directly reduce growth rate, physiological... |
| Tipo: Text |
Palavras-chave: Oyster model; Analytical model; Bivalve molluscs culture; Models. |
| Ano: 1993 |
URL: http://archimer.ifremer.fr/doc/1993/publication-6104.PDF |
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| Sohngen, Brent; Sedjo, Roger A.. |
| In this paper, we compare and contrast two types of timber models that have been used for public policy analysis. These models have been variously used to predict price, inventory and market welfare impacts under different exogenous forces that impact timber markets. The framework and theory for each model type is presented and discussed. We then thoroughly test the two model types across six potential exogenous shocks to timber markets, ranging from instantaneous demand shocks to gradual supply adjustments. Our comparison indicates that these models predict potentially important differences in timber market behavior. These differences are important to consider for those who do public policy analysis. |
| Tipo: Working or Discussion Paper |
Palavras-chave: Timber markets; Models; Dynamic adjustment; Optimization; Resource /Energy Economics and Policy; C62; Q21; Q23. |
| Ano: 1996 |
URL: http://purl.umn.edu/10467 |
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| Peterson, Garry; McGill University; garry.peterson@mcgill.ca; De Leo, Giulio A; Agenzia Regionale per la Protezione dell' Ambiente; deleo@dsa.unipr.it; Hellmann, Jessica J; Stanford University; jessicah@leland.stanford.edu; Janssen, Marco A; Indiana University; maajanss@indiana.edu; Kinzig, Ann; Arizona State University; Ann.Kinzig@asu.edu; Malcolm, Jay R; University of Toronto; jay.malcolm@utoronto.ca; O'Brien, Karen L; -; kobrien@online.no; Pope, Shealagh E; Environment Canada; shealagh.pope@ec.gc.ca; Rothman, Dale S; Columbia University; drothman@bio2.edu; Shevliakova, Elena; Carnegie Mellon University; lenish@cmu.edu; Tinch, Robert R.T.; York University, UK; rrtt100@york.ac.uk. |
| Tipo: Peer-Reviewed Reports |
Palavras-chave: Adaptive management; Climate change; Global change; Uncertainty; Models. |
| Ano: 1997 |
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| Hussain, Intizar; Marikar, Fuard; Jehangir, Waqar Ahmed. |
| A study of the enormous differences in agricultural productivity that exist across farms and regions in Pakistan, where, for example, recent farm-level data from Sindh, indicates that irrigated wheat output per hectare varies from 0.5 to 5.4 tons across farms. Looks at the central goal of agricultural policy in the country, viz. improving and sustaining productivity, narrowing the existing productivity gaps, and enhancing resource use efficiencies to meet food requirements of a rapidly growing population. |
| Tipo: Report |
Palavras-chave: Irrigated farming; Wheat; Productivity; Performance evaluation; Water management; Cropping systems; Water supply; Soil properties; Models; Pakistan; Lower Indus Basin; Agribusiness; Agricultural Finance; Crop Production/Industries; Environmental Economics and Policy; Farm Management; Production Economics; Productivity Analysis. |
| Ano: 2000 |
URL: http://purl.umn.edu/53023 |
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| Hussain, Intizar; Marikar, Fuard; Jehangir, Waqar Ahmed. |
| A study of the enormous differences in agricultural productivity that exist across farms and regions in Pakistan, where, for example, recent farm-level data from Sindh, indicates that irrigated wheat output per hectare varies from 0.5 to 5.4 tons across farms. Looks at the central goal of agricultural policy in the country, viz. improving and sustaining productivity, narrowing the existing productivity gaps, and enhancing resource use efficiencies to meet food requirements of a rapidly growing population. |
| Tipo: Report |
Palavras-chave: Irrigated farming; Wheat; Productivity; Performance evaluation; Water management; Cropping systems; Water supply; Soil properties; Models; Pakistan; Lower Indus Basin; Community/Rural/Urban Development; Crop Production/Industries; Demand and Price Analysis; Environmental Economics and Policy; Farm Management; Production Economics; Productivity Analysis. |
| Ano: 2000 |
URL: http://purl.umn.edu/53024 |
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| Sedjo, Roger A.; Sohngen, Brent. |
| Forestry has been considered to have potential in reducing the atmospheric concentration of carbon dioxide by sequestrating carbon in above-ground timber and below-ground roots and soil. This potential has been noted in the Kyoto Protocol, which identified specific forestry activities for which carbon sequestration credits could be obtained. To date, a few forestry efforts have been undertaken for carbon purposes, but most of these efforts have been on a small scale. Proposals have been under discussion, however, that would result in the creation of very large areas of new forest for the purpose of offsetting some of the additional carbon that is being released into the atmosphere. Concerns are expressed, however, that large-scale sequestration operations... |
| Tipo: Working or Discussion Paper |
Palavras-chave: Carbon; Forests; Sequestration; Leakages; Timber markets; Prices; Models; Resource /Energy Economics and Policy; Q10; Q15; Q21; Q23; Q24. |
| Ano: 2000 |
URL: http://purl.umn.edu/10778 |
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| Registros recuperados: 103 | |
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