| 193681. |
- Sparnins, Edgars, et al.
(författare)
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Transverse cracking mastercurve of cross-ply laminated composites
- 2008
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Ingår i: Advances in Heterogeneous Material Mechanics. - Lancaster, Pa : DEStech Publications, Inc.. - 9781932078800 ; , s. 1284-1287
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Konferensbidrag (refereegranskat)abstract
- Progressive cracking of a transverse layer in a cross-ply composite laminate subjected to tensile loading is considered. Using the results of a probabilistic cracking model, approximate relations for crack density as a function of stress are derived for initiation-controlled cracking. It is shown that the crack density evolution in the transverse ply can be represented by a mastercurve in suitably normalized coordinates. The mastercurve approach is applied to progressive cracking in glass/epoxy laminates.
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| 193682. |
- Sparovek, Gerd, 1962, et al.
(författare)
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Asymmetries of cattle and crop productivity and efficiency during Brazil's agricultural expansion from 1975 to 2006
- 2018
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Ingår i: Elementa. - : University of California Press. - 2325-1026. ; 6
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Tidskriftsartikel (refereegranskat)abstract
- Brazil has global importance for food production and conservation of natural resources. The country has plans to increase yields and commitments to decrease deforestation that require higher productivity. Plans and policies for the growth of Brazilian agriculture, however, have been made without an integrated analysis of the harvest and not supported by a universal metric regarding its efficiency. Applying methods to model flows of energy and matter along food supply chains for agricultural production from 1975 to 2006, we found that crop and cattle harvests and their productivity have increased during the last four decades in consolidated and deforestation frontier regions. Yet in 2006, crop protein production was 20 times larger than cattle protein, using an area 2.6 times smaller than pastures. Crop protein productivity was 0.25 ton.ha(-1) with emissions of 2 ton GHG per ton of protein, while cattle productivity was 0.01 ton.ha(-1) with emissions of 283 ton GHG per ton of protein. From 1975 to 2006, the portion of crop protein and energy going to feed increased while the portion going to direct human consumption decreased. Our findings suggest that more efficient food systems would be achieved by a combination of intensification of cattle systems, optimization of feed-meat systems and an increase in the share of the consumption of crops as a source of protein. We suggest an initial road map to the expansion of the cultivated area and intensification of agriculture for zero deforestation, efficient and sustainable land use and food systems where cattle pasture intensification is a transition that will last until the expansion of crops replace all pasture present on suitable arable land. During this transition, pasture area will decrease until it is limited only to marginal non-arable lands. Such change could be achieved by a robust strategy that combines penalties and incentives and prevents the risks of a rebound effect for the intensification of agriculture.
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| 193683. |
- Sparovek, G., et al.
(författare)
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Brazilian Agriculture and Environmental Legislation: Status and Future Challenges
- 2010
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Ingår i: Environmental Science & Technology. - : American Chemical Society (ACS). - 0013-936X .- 1520-5851. ; 44:16, s. 6046-6053
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Tidskriftsartikel (refereegranskat)abstract
- Brazilian agriculture covers about one-third of the land area and is expected to expand further We assessed the compliance of present Brazilian agriculture with environmental legislation and identified challenges for agricultural development connected to this legislation We found (i) minor illegal land use in protected areas under public administration, (ii) a large deficit in legal reserves and protected riparian zones on private farmland, and large areas of unprotected natural vegetation in regions experiencing agriculture expansion Achieving full compliance with the environmental laws as they presently stand would require drastic changes in agricultural land use, where large agricultural areas are taken out of production and converted back to natural vegetation The outcome of a full compliance with environmental legislation might not be satisfactory due to leakage, where pristine unprotected areas become converted to compensate for lost production as current agricultural areas are reconverted to protected natural vegetation. Realizing the desired protection of biodiversity and natural vegetation, while expanding agriculture to meet food and biofuel demand, may require a new approach to environmental protection New legal and regulatory instruments and the establishment of alternative development models should be considered
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| 193684. |
- Sparovek, G., et al.
(författare)
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Environmental, land-use and economic implications of Brazilian sugarcane expansion 1996-2006
- 2009
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Ingår i: Mitigation and Adaptation Strategies for Global Change. - : Springer Science and Business Media LLC. - 1381-2386 .- 1573-1596. ; 14:3, s. 285-298
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Tidskriftsartikel (refereegranskat)abstract
- Governments are promoting biofuels and the resulting changes in land use and crop reallocation to biofuels production have raised concerns about impacts on environment and food security. The promotion of biofuels has also been questioned based on suggested marginal contribution to greenhouse gas emissions reduction, partly due to induced land use change causing greenhouse gas emissions. This study reports how the expansion of sugarcane in Brazil during 1996-2006 affected indicators for environment, land use and economy. The results indicate that sugarcane expansion did not in general contribute to direct deforestation in the traditional agricultural region where most of the expansion took place. The amount of forests on farmland in this area is below the minimum stated in law and the situation did not change over the studied period. Sugarcane expansion resulted in a significant reduction of pastures and cattle heads and higher economic growth than in neighboring areas. It could not be established to what extent the discontinuation of cattle production induced expansion of pastures in other areas, possibly leading to indirect deforestation. However, the results indicate that a possible migration of the cattle production reached further than the neighboring of expansion regions. Occurring at much smaller rates, expansion of sugarcane in regions such as the Amazon and the Northeast region was related to direct deforestation and competition with food crops, and appear not to have induced economic growth. These regions are not expected to experience substantial increases of sugarcane in the near future, but mitigating measures are warranted.
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| 193685. |
- Sparovek, G., et al.
(författare)
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Sugarcane ethanol production in Brazil: An expansion model sensitive to socioeconomic and environmental concerns
- 2007
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Ingår i: Biofuels, Bioproducts and Biorefining. - : Wiley. - 1932-1031 .- 1932-104X. ; 1:4, s. 270-282
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Tidskriftsartikel (refereegranskat)abstract
- Brazilian agriculture is characteristically dynamic; land and production resources have a skewed ownership distribution; and agricultural production is essential for small holders of rural poor regions. Also, the main agricultural land use is composed of pastures where extensive livestock production prevails. Because of increasing demand Brazil is expected to expand its sugarcane-based ethanol production. Addressing concerns about social and environmental impacts of such an expansion requires careful consideration of the complexity of Brazilian agriculture in general and specific local conditions in particular. This perspective outlines an expansion model for sugarcane ethanol production that is sensitive to socioeconomic and environmental concerns. Through integration with the prevailing land use, the model avoids the usual displacement of extensive livestock production to remote regions, causing leakage effects with deforestation and promotes milk and beef cattle intensification and investment opportunities for local society. The expansion model is feasible at current market conditions and should have good prospects for complying with sustainability criteria within various certification schemes presently under development. A case study, developed in the Pontal do Paranapanema region (state of São Paulo, Brazil) illustrates the model in agrarian reform settlements. © 2007 Society of Chemical Industry and John Wiley & Sons, Ltd.
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| 193686. |
- Sparovek, Gerd, 1962, et al.
(författare)
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Sustainable bioproducts in Brazil: disputes and agreements on a common ground agenda for agriculture and nature protection
- 2016
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Ingår i: Biofuels, Bioproducts and Biorefining. - : Wiley. - 1932-1031 .- 1932-104X. ; 10:3, s. 204-221
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Tidskriftsartikel (refereegranskat)abstract
- A key question for food, biofuels, and bioproducts production is how agriculture affects the environment, and social and economic development. In Brazil, a large agricultural producer and among the biologically wealthiest of nations, this question is challenging and opinions often clash. The Brazilian parliament and several stakeholders have recently debated the revision of the Forest Act, the most important legal framework for conservation of natural vegetation on Brazilian private agricultural lands. Past decades have shown improvements in the agricultural sector with respect to productivity and efficiency, along with great reductions in deforestation and growth of environmentally certified production. However, the opposing sides in the debate have ignored this progress and instead continue to entrench their respective combative positions. A structured exchange involving nine experts associated with major producer interests (livestock, crops, planted forest, and charcoal) and environmental NGOs was moderated based on a framework that sorted viewpoints into four categories: (i) common ground - compatible interests considered to be high priority for Brazilian sustainable agricultural development; (ii) serving exclusive nature conservation interest; (iii) serving exclusive agricultural production interest; and (iv) mainly serving the purpose of sustaining dispute. We conclude that the majority of actions and expected future trends reflect achievements and ambitions to balance production and conservation, but much public opinion - and in turn decisions in the parliament and government for agriculture and conservation - is shaped by a perceived conflict between these objectives and a debate that has become, at least to some extent, an end in itself.
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| 193687. |
- Sparovek, G., et al.
(författare)
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The revision of the Brazilian Forest Act: increased deforestation or a historic step towards balancing agricultural development and nature conservation?
- 2012
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Ingår i: Environmental Science and Policy. - : Elsevier BV. - 1873-6416 .- 1462-9011. ; 16, s. 65-72
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Tidskriftsartikel (refereegranskat)abstract
- Almost two-thirds of the Brazilian territory still has prevalence of natural vegetation. Although not all pristine, much of these areas have high conservation value. 170 million hectare (Mha) of the natural vegetation is located within Federal and State protected areas. Most of the remaining 367 Mha is on private agriculture lands, where the Forest Act is the most important legal framework for conservation. In July 2010, the Brazilian parliament began the analysis of a substitutive legislation for the Forest Act. The main motivations for the revision is that, on the one hand, it has been found ineffective in protecting natural vegetation, and on the other hand, it is perceived as a barrier against development in the agriculture sector. The substitutive Forest Act, as it presently stands, does not represent a balance between existing standpoints and objectives; it may drive development towards either more private protection through market-driven compensation actions, or increased deforestation and less nature protection/restoration. This article uses outcomes from modeling analyses to discuss weaknesses of the substitutive Forest Act and to suggest possible improvements.
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| 193688. |
- Sparr, Gunnar, et al.
(författare)
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Discontinuity preserving visual reconstruction by means of potential theory
- 1990
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Ingår i: Pattern Recognition Letters. - 0167-8655. ; 11:2, s. 117-122
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Tidskriftsartikel (refereegranskat)abstract
- Discontinuity preserving interpolation methods are often desirable in image reconstruction from sparse visual data. Two such schemes are constructed by interpreting the image as the potentialcause by some distribution of charges, and then detecting certain patterns (notably dipole curves) among the charges. Experiments have been performed on an ink-jet plotter, showing good performance.
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| 193689. |
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| 193690. |
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