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Biological control of invasive plant species: stochastic economic analysis AgEcon
Chalak-Haghighi, Morteza; Ruijs, Arjan; van Ierland, Ekko C..
We analysed to what extent the stochastic effects of two biological control agents (i.e. weevils and mycoherbicides) affect the optimal choice of Californian thistle control. A stochastic, dynamic optimisation model was set up to analyse strategies that maximise the expected net present values. We analysed the cost-effective strategies to control the thistle for deterministic and stochastic cases. Results show that the stochasticity of the efficacy of weevils does not affect the optimal strategy. Compared to the deterministic case, however, mycoherbicides will be introduced at a higher level of weed density if we take the stochastic effect of mycoherbicides into account.
Tipo: Conference Paper or Presentation Palavras-chave: Stochastic; Optimisation; Biological control; Californian thistle; Economics..
Ano: 2009 URL: http://purl.umn.edu/48153
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Competition, Evolution and Optimisation: Comparisons of Models in Economics and Ecology AgEcon
Tisdell, Clement A..
Discusses concepts of competition in economics and ecology and the relevance of evolution to both subjects. It is suggested that although speciation or increasing biodiversity tends to occur in undisturbed ecological systems, the opposite trend may occur in economic systems. Competition based on optimisation plays a significant role in theories of the evolution of species and some theories of the evolution of business or industrial structures. But evolution does not result in optimal selection of species or businesses for the future, and there is scope for doubt about what is being optimised by survivors in the evolutionary process. Ecological or biological theories of intra-specific competition involving scramble and contest competition are outlined and...
Tipo: Working or Discussion Paper Palavras-chave: Biology; Competition; Evolution; Market development; Optimisation; Environmental Economics and Policy.
Ano: 2001 URL: http://purl.umn.edu/48384
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Determinación del óptimo económico en la producción de "setas" (Pleurotus ostreatus) Colegio de Postgraduados
Alemán Morales, Mireya.
La producción de “setas” (Pleurotus ostreatus), es una alternativa para producir y diversificar los alimentos que requiere la población en México. En el país es escasa la información acerca de la rentabilidad de éste cultivo. Por ello, el objetivo de este trabajo fue estimar una función de producción que muestre matemáticamente la relación funcional entre los insumos productivos utilizados y la producción “setas”. La variable dependiente la constituyó la producción de “setas” producidas y la variable independiente fueron las bolsas en producción. Los resultados económicos mostraron que la etapa de producción II, la que es económicamente relevante, se inicia en el punto donde se encuentran en el área de producción 2449 bolsas y termina donde el producto...
Tipo: Tesis Palavras-chave: Función de producción; Pleurotus ostreatus; Optimización; Rentabilidad; “setas”; Production function; Pleurotus ostreatus; Optimisation; Viability; “mushrooms”.
Ano: 2008 URL: http://hdl.handle.net/10521/1417
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Economics of controlling a spreading environmental weed AgEcon
Chalak-Haghighi, Morteza; Pannell, David J..
Weeds can cause significant problems to natural ecosystems. Although there have been numerous studies on the economics of weed control, relatively few of these studies have focused on natural ecosystems. This paper addresses this gap in the literature by assessing the cost-effectiveness of a comprehensive range of control strategies for blackberry (Rubus anglocandicans) in natural environments in Australia. We developed a stochastic dynamic simulation model and a deterministic dynamic optimisation model. The stochastic model calculates the expected net present value (NPV) of a range of control strategies, including any combination of treatment options. The optimisation model identifies the treatment combination that maximises NPV. Both models represent the...
Tipo: Conference Paper or Presentation Palavras-chave: Environment; Economics; Weed; Stochastic; Optimisation; Management; Environmental Economics and Policy.
Ano: 2010 URL: http://purl.umn.edu/58886
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Economics of controlling a spreading environmental weed AgEcon
Chalak, Morteza; Pannell, David J..
Weeds can cause significant problems to natural ecosystems. Although there have been numerous studies on the economics of weed control, relatively few of these studies have focused on natural ecosystems. This paper addresses this gap in the literature by assessing the cost-effectiveness of a comprehensive range of control strategies for blackberry (Rubus anglocandicans) in natural environments in Australia. We developed a stochastic dynamic simulation model and a deterministic dynamic optimisation model. The stochastic model calculates the expected net present value (NPV) of a range of control strategies, including any combination of treatment options. The optimisation model identifies the treatment combination that maximises NPV. Both models represent the...
Tipo: Working or Discussion Paper Palavras-chave: Environment; Economics; Weed; Stochastic; Optimisation; Management; Environmental Economics and Policy.
Ano: 2011 URL: http://purl.umn.edu/108416
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Economics of controlling invasive species: a stochastic optimisation model for a spatial-dynamic process AgEcon
Chalak, Morteza; Pannell, David J.; Polyakov, Maksym.
Invasive species are significant threats to biodiversity, natural ecosystems and agriculture leading to large worldwide economic and environmental damage. Spread and control of invasive species are stochastic processes with important spatial dimensions. Most economic studies of invasive species control ignore spatial and stochastic aspects. This paper covers this gap in the previous studies by analysing a spatially explicit dynamic process of controlling invasive species in a stochastic setting. We show how stochasticity, spatial location of infestation and control can influence the spread, control efficiency and optimal control strategies. The main aim of this paper is to analyse the relationship between economic parameters and stochastic spatial...
Tipo: Conference Paper or Presentation Palavras-chave: Spatial; Dynamics; Invasive; Economics; Stochastic; Optimisation; Environmental Economics and Policy.
Ano: 2011 URL: http://purl.umn.edu/103325
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Energianövények szántóföldi termelésének optimalizálása AgEcon
Bedene Szoke, Eva; Mohamed, Zsuzsanna.
Az általunk kidolgozott Biomassza Termelési Modell (BTM) lineáris programozáson alapul, és lehetővé teszi, hogy adott mezőgazdasági területre vonatkozóan meghatározzák az optimális vetésszerkezetet, különböző célfüggvények mellett. A különböző célfüggvények esetére vonatkozó optimalizálást a gazdasági környezet, különösen a szabályozó rendszer változása miatt tartottuk szükségesnek, amely adott körülmények között a legkedvezőbb gazdasági haszonnal jár. A döntés fő kérdése, hogy a rendelkezésre álló földterület és erőforrás-kapacitás mellett élelmiszercélú, vagy inkább energetikai célú hasznosítás irányában célszerű-e elmozdulni. --------------------------------------- We have developed a Biomass Production Model (BTM), which is based on linear programming....
Tipo: Journal Article Palavras-chave: Biomassza-termelés; LP modell; Optimalizálás.; Biomass production; LP model; Optimisation; Land Economics/Use; Production Economics; Research Methods/ Statistical Methods.
Ano: 2010 URL: http://purl.umn.edu/99135
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Etude numérique du train de pêche d'un chalutier (DEA) ArchiMer
Theret, Francois.
IFREMER aims at digitalizing trawl gear in order to reach two goals: on the one hand, participating in the realisation of a computer assisted trawl conception software; on the other hand, being able to study quickly and easily the influence of different adjustment parameters on the shape of the trawl in order to indicate to the skipper, if possible in real time, the optimal adjustment for the conditions he's in. From an international point of view, there are only two strategies to approach this problem: - the first strategy is based on statistical studies on the existing nets (almost limited to their reproduction on different scales), but this approach does not leave much room for innovation as it can only be applied to the same type of nets as those that...
Tipo: Text Palavras-chave: Experimentation; Optimization; Adjustment; Hydrodynamic; Modelization; Trawl gear; Trawl; Expérimentation; Maquette de chalut; Optimisation; Réglage; Hydrodynamique; Modèle numérique; Train de pêche; Chalut.
Ano: 1990 URL: http://archimer.ifremer.fr/doc/1990/these-3627.pdf
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La conception de structures navales en sandwich: Un probleme inverse ArchiMer
Holm, D; Esping, B; Romell, O; Campion, F.
An integrated approach is introduced for the solution of the inverse problem: which are the lamina orientation, laminate constitution, core quality and thickness combination ensuring specified objective(s) to be reached? The optimal solution is obtained using mathematically stringent optimization methods (the Method of Moving Asymptotes, MMA) coupled with finite element analysis, interactive graphic pre- and post-processing and parametric modelling, as implemented in OASIS-ALADDIN. This approach has been applied to the optimal design of the hull structure of a Surface Effect Ship made of GRP-sandwich. The objective was to minimize the weight of the ship by determining the optimum skin and core thicknesses of structural members of the hull as well as web...
Tipo: Text Palavras-chave: Finite element method; Glass reinforced plastics; Ship hulls; Safety devices; Ship technology; Ship design; Composite materials; Sandwich; Composite; Problème inverse; Sensibilité; Optimisation.
Ano: 1992 URL: http://archimer.ifremer.fr/doc/1992/acte-1054.pdf
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Minimising costs of environmental service provision: water-yield, salt-load and biodiversity targets with new tree planting in Simmons Creek Catchment, NSW, a dryland farming/grazing area. AgEcon
Nordblom, Thomas L.; Hume, Iain H.; Cresswell, Hamish; Glover, Mark; Hean, Robyn L.; Finlayson, John D.; Wang, Enli.
Although dryland farming and grazing have been practiced for over 130 years in the 17,000 ha Simmons Creek catchment without surface salinity problems, the area has been identified as a significant source of salt seepage to Billabong Creek in the NSW Murray catchment. Groundwater movement and salinity levels are spatially heterogenous at Simmons Creek. Groundwater of the upper catchment is relatively fresh and seemingly unconnected with the highly saline groundwater of the lower catchment. However, fresh surface water does flow from the upper to the lower catchment. This spatial diversity provokes the question of where high-water-use forest habitats might be placed to achieve different combinations of environmental services (greater water yield, lower...
Tipo: Conference Paper or Presentation Palavras-chave: Optimisation; Opportunity costs; Forest-habitat; Environmental services; Environmental Economics and Policy.
Ano: 2007 URL: http://purl.umn.edu/10357
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Minimizing flight time and fuel consumption for airborne crop spraying CIGR Journal
Kamal, Syed Shariq; Jackman, Patrick; Grieve, Bruce.
Abstract: With the world’s growing population and increase in urbanization, the requirement for optimized agriculture has increased.  Agricultural operations such as crop spraying and water management require rigorous monitoring of crops in order to identify the correct time to spray and irrigate the crops.  Thus managing vast properties require an affordable spraying strategy.  Advancement in computer processing speed and algorithms has made it possible to devise such strategies to optimize several agricultural operations.  One of those operations is to spray crops with pesticides and monitor crops.  This requires an airborne vehicle which can monitor and spray crops efficiently.  Several optimization techniques have been used in recent years to optimize...
Tipo: Info:eu-repo/semantics/article Palavras-chave: Crop spraying; Optimisation; Airborne vehicles; Pesticides; Artificial intelligence; United Kingdom..
Ano: 2014 URL: http://www.cigrjournal.org/index.php/Ejounral/article/view/2368
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Numerical optimisation of trawls design to improve their energy efficiency ArchiMer
Priour, Daniel.
Trawls energy efficiency is greatly affected by the drag, as well as by the swept area regarding pelagic trawls and by the swept width for bottom ones. The drag results in an increase of the energy consumption and the sweeping influences the catch. In order to reduce the drag per swept area (or width) a numerical tool dedicated to the automatic optimisation of the trawl design has been developed. Based on a finite element method model for flexible netting structures, the tool modifies step by step a reference design. For each step the best-modified design, in terms of drag per swept area (or width), is kept. Such a methodology was used in two cases: which show a 43% increase in energy efficiency regarding the pelagic trawl case and 27% for the bottom trawl...
Tipo: Text Palavras-chave: Swept width; Swept area; Drag; Fuel consumption; Optimisation; Modelling; Trawl; Fishing gears.
Ano: 2009 URL: http://archimer.ifremer.fr/doc/2009/publication-6583.pdf
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Optimal control of a stochastic biological invasion AgEcon
Chalak, Morteza; Pannell, David J..
Although there have been numerous studies on the economics of weed control, relatively few of these studies have focused on natural ecosystems. The aims of this papers are: A) to identify the combination of control options that is optimal for blackberry (Rubus anglocandicans) in Australian natural ecosystems, B) to assess whether an integrated control strategy is superior to chemical-only strategies, C) to evaluate the economic net benefits of specific biologically oriented control methods (a rust and grazing by goats), D) to determine how changes in model parameters affect the optimal control strategy. To address these aims, a stochastic dynamic simulation model and a stochastic dynamic programming model are developed. The results indicate that, while an...
Tipo: Presentation Palavras-chave: Environment; Economics; Weed; Stochastic; Optimisation; Management; Environmental Economics and Policy.
Ano: 2012 URL: http://purl.umn.edu/124373
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Optimisation de procédés innovants pour l'obtention de phycocolloïdes ArchiMer
Vauchel, Peggy.
Alginates are polysaccharides which are naturally present in the cell wall of brown algae and extracted because of their rheological properties. The alginate industry uses an extraction protocol, which central step, the carbonatation, is conducted in batch reactors. It is a high water, reagent and time demanding process. The main objective of this thesis is to optimize the alginate extraction process. A study of the existing process, focused on carbonatation step, enabled to highlight points which could be enhanced to optimize the extraction yield and the quality of extracted alginates. Stirring intensity and algae pieces size have been identified as parameters having an influence on the carbonatation reaction kinetics. A specific analysis on medullar and...
Tipo: Text Palavras-chave: Alginate; Extraction; Laminaria digitata; Extrusion réactive; Optimisation; Modélisation; Distribution des temps de séjour; Cinétique; Rendement; Propriétés rhéologiques; Alginate; Extraction; Laminaria digitata; Reactive extrusion; Optimization; Modeling; Residence time distribution; Kinetics; Extraction yield; Rheological properties.
Ano: 2007 URL: http://archimer.ifremer.fr/doc/00002/11364/7937.pdf
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Optimisation methods for assisting policy decisions on endemic diseases AgEcon
Stott, Alistair W..
Endemic disease of animals is an economic problem as it deprives humans of scarce resources that might otherwise satisfy human wants. Optimisation methods identify the strategies that minimise this economic problem. Given the potentially vast extent of the deprivation, not only in terms of lost wealth but also in terms of animal welfare, human health and environmental damage, this subject offers great benefits to decision-makers from the individual farm to the global level. This paper uses examples to illustrate the basic economic principles concerned. It shows how these principles may be extended to deal with current limitations in theory and practice. Lack of data is a common problem that may be dealt with by using computer simulation, theoretical...
Tipo: Working or Discussion Paper Palavras-chave: Economics; Decision analysis; Optimisation; Modelling; Endemic disease; Knowledge transfer; Health Economics and Policy.
Ano: 2006 URL: http://purl.umn.edu/46000
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Optimisation of trawl energy efficiency under fishing effort constraint ArchiMer
Priour, Daniel; Khaled, Ramez.
Trawls energy efficiency is greatly affected by the drag, as well as by the swept area. The drag results in an increase of the energy consumption and the sweeping influences the catch. Methods of optimisation of the trawl design have been developed in order to reduce the volume of carburant per kg of caught fish and consequently the drag per swept area of the trawl. Based on a finite element method model for flexible netting structures, the tool modifies step by step a reference design. For each step the best-modified design, in terms of drag per swept area is kept. Such optimisation can lead to a decrease of the drag or an increase of the swept area. In the second case, that could lead to an increase of fishing effort. To avoid such increase, which could...
Tipo: Text Palavras-chave: Fishing; Fuel; Fishing gear; Trawl; Optimisation; Fishing effort.
Ano: 2009 URL: http://archimer.ifremer.fr/doc/00170/28151/26381.pdf
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Optimising the spatial pattern of landscape revegetation AgEcon
Polyakov, Maksym; Pannell, David J.; Rowles, Alexei; Park, Geoff; Roberts, Anna M..
The spatial pattern of landscape reconstruction makes a substantial difference to environmental outcomes. We develop a spatially explicit bio-economic model that optimises the reconstruction of a heavily cleared landscape through revegetation. The model determines the spatial priorities for revegetation that minimises economic costs subject to achieving particular improvements in habitat for 29 woodland-dependent bird species. The study focuses on the Avoca catchment (330 thousand ha) in North-Central Victoria. Our model incorporates spatial pattern and heterogeneity of existing and reconstructed vegetation types. The revegetation priorities are identified as being: sites in the vicinity of existing remnants, riparian areas, and parts of the landscape with...
Tipo: Conference Paper or Presentation Palavras-chave: Landscape reconstruction; Biodiversity; Optimisation; Habitat; Environmental Economics and Policy; Land Economics/Use; Q57.
Ano: 2011 URL: http://purl.umn.edu/100697
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Rent-Maximization versus Competition in the Western and Central Pacific Tuna Fishery AgEcon
Hannesson, Rognvaldur; Kennedy, John O.S..
Where a fish stock straddles or migrates between country A's exclusive economic zone (EEZ) and country B's EEZ, or the high seas, vesting ownership rights in the stock with A does not ensure efficient harvesting of the stock. This problem arises in the case of migratory tuna stocks in the Western and Central Pacific Ocean (WCPO). Four species of tuna reside for only part of the year in the EEZs of coastal states, many of which are Pacific Island Countries (PICs). Most of the harvesting of the stocks is carried out by distant water fishing nations such as the USA, Japan, Taiwan, China and Korea. Problems arise for achieving efficiency and equity in the harvesting of the stocks by disparate countries. The problems are made more difficult by changes in the...
Tipo: Conference Paper or Presentation Palavras-chave: Bioeconomic modelling; Game theory; Optimisation; Migratory tuna; Resource /Energy Economics and Policy.
Ano: 2007 URL: http://purl.umn.edu/9458
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RVA as a tool for optimisation of cassava starch manufacturing regarding to SO2 application and storage time Thai Agricultural
Sriroth, K.; Walapatit, S.; Piyachomkwan, K.; Oates, C.G..
Palavras-chave: Cassava; Starc; Manufacturing; Optimisation.
Ano: 1998 URL: http://anchan.lib.ku.ac.th/agnet/handle/001/4839
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Wie viel bringt eine verbesserte Produktionsprogrammplanung auf der Grundlage einer systematischen Auswertung empirischer Zeitreihen? – Die Bedeutung von Prognosemodellen bei der Optimierung unter Unsicherheit AgEcon
Musshoff, Oliver; Hirschauer, Norbert.
In this paper we examine whether there is room for improvement in farm program decisions through the integration of formal mathematical optimisation into the planning process. Probing the potential for improvement, we investigate the cases of four Brandenburg cash crop farms over the last six years. We find that their total gross margins could have been increased significantly through a more sophisticated program planning. However, we also find that the superiority of formalised planning approaches depends on the quality of the data. The superior formal planning approach includes, in contrast to farmers’ ad hoc planning, a systematic time series analysis of gross margins and a stochastic optimisation model. For each of the six years, the formal planning...
Tipo: Journal Article Palavras-chave: Planning of the production program; Optimisation; Uncertainty; Static distributions; Stochastic processes; Farm Management; Risk and Uncertainty.
Ano: 2006 URL: http://purl.umn.edu/97196
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