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A Comparison of Timber Models for Use in Public Policy Analysis AgEcon
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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A Flexible Inventory Model for MSW Recycling AgEcon
Louis, Garrick; Shih, Jhih-Shyang.
Most of the United States have laws mandating the recycling of municipal solid waste (MSW). In order to comply, municipalities recycle quotas of materials, without regard to fluctuating prices. An inventory system is proposed that allows municipalities to be sensitive to materials prices as they recycle in accordance with state mandates. A dynamic model is developed; it uses historical secondary material prices as exogenous inputs to minimize the net present value of MSW recycling system cost. The model provides a cost-effective method for municipalities to achieve their MSW recycling targets. The savings is approximately $1.43 per ton of MSW generated based on total MSW management costs of $13.5 per ton. The model also allows one to investigate the...
Tipo: Working or Discussion Paper Palavras-chave: Municipal solid waste; Recycling; Inventory; Optimization; Environmental Economics and Policy; Q2.
Ano: 2002 URL: http://purl.umn.edu/10459
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A Watershed-Based Economic Model of Alternative Management Practices in Southern Agricultural Systems AgEcon
Paudel, Krishna P.; Hite, Diane; Intarapapong, Walaiporn; Susanto, Dwi.
We investigated the environmental impacts of alternative cultural practices within a watershed under different water quality standards. We used experimental data on nutrient runoff to determine the optimal amount of broiler litter application in hay production in Louisiana. To compensate for the lack of experimental data, we used biophysical simulation models to find the optimal combination of agricultural best-management practices in a watershed in Mississippi. The results indicated that stricter environmental standards lower total profit potential and litter utilization.
Tipo: Journal Article Palavras-chave: Broiler litter; Cropping systems; Optimization; Watershed level modeling; Water quality; C6; Q1; Q25; D21.
Ano: 2003 URL: http://purl.umn.edu/43213
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An Assessment of the Precision and Confidence of Aquatic Eddy Correlation Measurements ArchiMer
Donis, Daphne; Holtappels, Moritz; Noss, Christian; Cathalot, Cecile; Hancke, Kasper; Polsenaere, Pierre; Wenzhoefer, Frank; Lorke, Andreas; Meysman, Filip J. R.; Glud, Ronnie N.; Mcginnis, Daniel F..
The quantification of benthic fluxes with the aquatic eddy correlation (EC) technique is based on simultaneous measurement of the current velocity and a targeted bottom water parameter (e.g., O2, temperature). High-frequency measurements (64 Hz) are performed at a single point above the seafloor using an acoustic Doppler velocimeter (ADV) and a fast-responding sensor. The advantages of aquatic EC technique are that 1) it is noninvasive, 2) it integrates fluxes over a large area, and 3) it accounts for in situ hydrodynamics. The aquatic EC has gained acceptance as a powerful technique; however, an accurate assessment of the errors introduced by the spatial alignment of velocity and water constituent measurements and by their different response times is...
Tipo: Text Palavras-chave: Turbulence; Boundary layer; Fluxes; Instrumentation/sensors; Optimization; Experimental design.
Ano: 2015 URL: http://archimer.ifremer.fr/doc/00275/38577/37102.pdf
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An empirical comparison of different risk measures in portfolio optimization AgEcon
Hoe, Lam Weng; Saiful Hafizah, Jaaman; Zaidi, Isa.
Risk is one of the important parameters in portfolio optimization problem. Since the introduction of the mean-variance model, variance has become the most common risk measure used by practitioners and researchers in portfolio optimization. However, the mean-variance model relies strictly on the assumptions that assets returns are multivariate normally distributed or investors have a quadratic utility function. Many studies have proposed different risk measures to overcome the drawbacks of variance. The purpose of this paper is to discuss and compare the portfolio compositions and performances of four different portfolio optimization models employing different risk measures, specifically the variance, absolute deviation, minimax and semi-variance. Results...
Tipo: Journal Article Palavras-chave: Portfolio; Optimization; Risk measures; Variance.; Financial Economics; CO2; C61; G11.
Ano: 2010 URL: http://purl.umn.edu/95934
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Analysis of profitability and risk in new agriculture in a Himalayan watershed by using dynamic non-linear programming model AgEcon
Sharma, Rakesh Kumar; Sankhayan, Prem Lall; Singh, Ranveer.
Cropping pattern in the Himalayan region of India has undergone a significant change in the recent past. Introduction of horticultural crops of vegetables, fruits and flowers have led to more intensive agriculture. Such a change, resulting in higher incomes and improvements of the overall living conditions has, however, been accompanied with increased income risk. This emphasises a need for proper analysis of the cropping pattern, at an appropriate scale, such as, a micro watershed. This was achieved by constructing a dynamic non-linear programming model incorporating appropriate objective function, constraints and crop and livestock activity budgets along with risk component present in the gross returns. The model was then solved under alternate policy...
Tipo: Conference Paper or Presentation Palavras-chave: Cropping pattern; Gross margins; Himachal Pradesh; Optimization; Covariance; Crop Production/Industries; Farm Management; Research Methods/ Statistical Methods; Resource /Energy Economics and Policy; Risk and Uncertainty; C61; Q12; Q15.
Ano: 2009 URL: http://purl.umn.edu/51404
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Avaliação da viabilidade técnica e econômica da utilização de biomassas como fonte energética alternativa em fornos industriais AgEcon
Lima, Lilian Maluf de; Oliveira, Ana Maria Kefalas; Carletti, Paulo de Tarso Filho; Ferrari, Renata Cristina; Caixeta, Jose Vicente Filho.
This study, conducted along the year 2003, was held in the environment of a cement company plant located in the São Paulo State. That industry has used carbon black as predominant energetic source which besides resulting a huge emission of gases (CO and CO2) into the atmosphere, has been more expensive than some other alternatives of biomass sources. Taking into consideration the location of that plant, there was a large supply of available biomass to be used as alternative fuel for industrial ovens. Several biomasses were analyzed and it was concluded that the sugar cane bagasse and residues of wood (sawdust and woodchips) were the most appropriate alternatives to such an industry.
Tipo: Journal Article Palavras-chave: Biomass; Energy; Transport; Optimization; Resource /Energy Economics and Policy.
Ano: 2006 URL: http://purl.umn.edu/55310
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Bacterial Resistance and the Optimal Use of Antibiotics AgEcon
Laxminarayan, Ramanan.
The increasing resistance of harmful biological organisms (bacteria, parasites, and pests) to selection pressure from the widespread use of control agents such as antibiotics, antimalarials, and pesticides is a serious problem in both medicine and agriculture. Modeling resistance-or, conversely, the effectiveness of these control agents as a biological resource-yields insights into how these agents should be optimally managed to maximize their economic benefit to society. This paper uses a model of evolution of bacterial resistance to antibiotics-in which resistance places an evolutionary disadvantage on the resistant organism-to develop a simple sequential algorithm of optimal antibiotic use. Although the solution to this problem follows the...
Tipo: Working or Discussion Paper Palavras-chave: Antibiotic resistance; Natural resource; Optimization; Health Economics and Policy; I0; Q0.
Ano: 2001 URL: http://purl.umn.edu/10479
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Behaviour of a floc population during a tidal cycle: laboratory experiments and numerical modelling ArchiMer
Verney, Romaric; Lafite, Robert; Brun-cottan, Jean Claude; Le Hir, Pierre.
An approach combining laboratory experiments and numerical modelling was used to investigate the behaviour of a floc population during an idealized tidal cycle. The experiment was conducted on suspended sediments at a concentration of 93 mg l−1 collected in the field. It was based on a jar test device to reproduce tidal-induced turbulence and coupled with a CCD camera system and image post-processing software to monitor floc size distribution. At the same time, a 0D size-class based aggregation/fragmentation model (FLOCMOD) was developed to simulate changes in the floc population over the tidal cycle. Experimental results revealed strong variability of the behaviour of microfloc and macrofloc populations with respect to the varying shear rates observed in...
Tipo: Text Palavras-chave: Flocculation; Tidal cycle; Laboratory experiment; FLOCMOD; OD model; Sensitivity analysis; Optimization.
Ano: 2011 URL: http://archimer.ifremer.fr/doc/00027/13846/11020.pdf
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Biological Limits on Agricultural Intensification: An Example from Resistance Management AgEcon
Laxminarayan, Ramanan; Simpson, R. David.
When the application of pesticides places selective evolutionary pressure on pest populations, it can be useful to plant refuge areas-crop areas intended to encourage the breeding of pests that are susceptible to the pesticide. Renewed interest in refuge areas has arisen with recent advances in biotechnology and genetically modified (GM) crops. In this paper, we use a simple model of the evolution of pest resistance to characterize the socially optimal refuge strategy for managing pest resistance. We demonstrate some interesting analogies with other models of renewable resource management, such as those of fisheries. Among the analogous results are findings that maintaining what we might call "maximal sustainable susceptibility" is typically not...
Tipo: Working or Discussion Paper Palavras-chave: Pest resistance; Biotechnology; Optimization; Research and Development/Tech Change/Emerging Technologies; Q1; Q2.
Ano: 2000 URL: http://purl.umn.edu/10914
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Cable length optimization for trawl fuel consumption reduction ArchiMer
Khaled, Ramez; Priour, Daniel; Billard, Jean-yves.
A numerical method for optimization of the cable lengths in trawls with respect to the ratio between the estimated trawl drag and the predicted catch efficiency is developed and applied. The trawl cables of interest are warps, bridles, headline and footrope. The optimization algorithm applies an ordered sequential process changing one cable length at the time. It is assumed in the predictions that the catch efficiency of the trawl is proportional with the trawl mouth area. In a case study optimizing a bottom trawl used on a research vessel by applying the new method it is predicted that it would be possible to reduce the ratio between trawl drag and catch efficiency by up to 46% by optimizing the cable lengths. Thus this would enable a considerable...
Tipo: Text Palavras-chave: Bottom trawl; Modeling; Optimization; Fuel consumption; Drag; Swept area; Mouth surface; Fish distribution.
Ano: 2013 URL: http://archimer.ifremer.fr/doc/00130/24106/22857.pdf
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Carbon conversion efficiency and population dynamics of a marine algae–bacteria consortium growing on simplified synthetic digestate: First step in a bioprocess coupling algal production and anaerobic digestion ArchiMer
Vasseur, Christophe; Bougaran, Gael; Garnier, Matthieu; Hamelin, Jérôme; Leboulanger, Christophe; Le Chevanton, Myriam; Mostajir, Behzad; Sialve, Bruno; Steyer, Jean-philippe; Fouilland, Eric.
Association of microalgae culture and anaerobic digestion seems a promising technology for sustainable algal biomass and biogas production. The use of digestates for sustaining the growth of microalgae reduces the costs and the environmental impacts associated with the substantial algal nutrient requirements. A natural marine algae–bacteria consortium was selected by growing on a medium containing macro nutrients (ammonia, phosphate and acetate) specific of a digestate, and was submitted to a factorial experimental design with different levels of temperature, light and pH. The microalgal consortium reached a maximum C conversion efficiency (i.e. ratio between carbon content produced and carbon supplied through light photosynthetic C conversion and acetate)...
Tipo: Text Palavras-chave: Optimization; Nannochloris; Heterotrophic bacteria; Anaerobic digestion; Bioenergy.
Ano: 2012 URL: http://archimer.ifremer.fr/doc/00085/19642/17419.pdf
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Choice of optimum feedstock portfolio for a cellulosic ethanol plant – A dynamic linear programming solution AgEcon
Kumarappan, Subbu; Ivanic, Rasto.
When the lignocellulosic biofuels industry reaches maturity and many types of biomass sources become economically viable, management of multiple feedstock supplies – that vary in their yields, density (tons per unit area), harvest window, storage and seasonal costs, storage losses, transport distance to the production plant – will become increasingly important for the success of individual enterprises. The manager’s feedstock procurement problem is modeled as a multi-period sequence problem to account for dynamic management over time. The case is illustrated with a hypothetical 53 million annual US gallon cellulosic ethanol plant located in south west Kansas that requires approximately 700,000 metric dry tons of biomass. The problem is framed over 40...
Tipo: Conference Paper or Presentation Palavras-chave: Cellulosic ethanol; Feedstock; Switchgrass; Miscanthus; Corn stover; Optimization; Biofuels; Biomass; Energy; Renewable; Agribusiness.
Ano: 2009 URL: http://purl.umn.edu/49407
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Climate change impacts on crop risks and agricultural production in Finland AgEcon
Lehtonen, Heikki; Kujala, Sanna.
Climate Change is expected to improve crop production conditions significantly in northern Europe. In some studies a significant increase in agricultural production is expected in northern Europe while drought is becoming gradually more severe in Southern Europe and France due to climate change. Our analysis provides one of the first steps in evaluating the possible scale of changes in agricultural production and use of farm land in Finland, so far one of the least favoured agricultural areas in Europe. Drought in early summer and low temperature sum during growing period are currently the main growth limiting factors in Finland. Even though the early part of the growing period is likely to be dry also in the future, both mean and variance of crop yields...
Tipo: Conference Paper or Presentation Palavras-chave: Climate change; Agriculture; Risk aversion; Mean-variance analysis; Sector models; Optimization; Crop production; Finland; Crop Production/Industries; Environmental Economics and Policy; Risk and Uncertainty.
Ano: 2007 URL: http://purl.umn.edu/9259
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Departures from the physical optimality in the bronchial tree of rats (Rattus norvegicus) Biol. Res.
CANALS M,MAURICIO; ATALA,CRISTIAN; OLIVARES,RICARDO; NOVOA,FRANCISCO F; ROSENMANN,MARIO.
We studied the departure from the physical optimality of the bronchial tree of rats using both i) the minimum volume and power and ii) the minimum surface and drag criteria, considering the bronchial junction as the unit study based on Zamir's model for vascular trees. Our results show deviations of the junctions of the bronchial tree from the expected optimums in the proximal airway that can be explained by both, the turbulent or transitional flow regime, and the airway's necessity to distribute its terminal branches in the alveolar surface filling the thoracic volume. The departures of the observed values at the optimum for the minimum volume and power were significantly different than the obtained departure values for the minimum surface and drag...
Tipo: Journal article Palavras-chave: Lung; Junction optimality; Optimization; Broncography.
Ano: 2002 URL: http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0716-97602002000300015
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Desidratação osmótica de abacaxi aplicada à tecnologia de métodos combinados. Repositório Alice
AZEREDO, H. M. C.; JARDINE, J. G..
O objetivo deste trabalho foi a otimização do processo de desidratação osmótica de abacaxi, visando a obtenção de um produto com máxima perda de água e mínima incorporação de sólidos. O processo foi aplicado à Tecnologia de Métodos Combinados, em que a redução no pH e uso de conservantes, todos aplicados em baixos níveis, a fim de se obter um produto similar à fruta fresca.
Tipo: Artigo em periódico indexado (ALICE) Palavras-chave: Métodos combinados; Otimização; Osmotic dehydration; Optimization; Combined methods; Abacaxi; Desidratação Osmótica; Pineapples.
Ano: 2000 URL: http://www.alice.cnptia.embrapa.br/alice/handle/doc/7874
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Economic Feasibility of a Woody Biomass- Based Ethanol Plant in Central Appalachia AgEcon
Wu, Jinzhuo; Sperow, Mark; Wang, Jingxin.
A mixed-integer programming model is developed to assess the economic feasibility of siting a woody biomass-based ethanol facility in the central Appalachian hardwood region. The model maximizes the net present value (NPV) of a facility over its economic life. Model inputs include biomass availability, biomass handling system type, plant investment and capacity, transportation logistics, feedstock and product pricing, project financing, and taxes. Four alternative woody biomass handling systems, which include all processes from stand to plant, are considered. Eleven possible plant locations were identified based on site selection requirements. Results showed that the optimal plant location was in Buckhannon, West Virginia. The NPV of the plant with a...
Tipo: Journal Article Palavras-chave: Biofuels; Economic analysis; Ethanol; Optimization; Woody biomass; Crop Production/Industries.
Ano: 2010 URL: http://purl.umn.edu/99118
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Effect of vermicompost, worm-bed leachate and arbuscular mycorrizal fungi on lemongrass (Cymbopogon citratus (DC) Stapf.) growth and composition of its essential oil Electron. J. Biotechnol.
León-Anzueto,Elizabeth; Abud-Archila,Miguel; Dendooven,Luc; Ventura-Canseco,Lucía María Cristina; Gutiérrez-Miceli,Federico A.
The objective of this study was to investigate the effect of vermicompost, worm-bed leachate (WBL) and Glomus mosseae, an arbuscular mycorrhizal fungi (AMF), on growth of lemongrass (Cymbopogon citratus (DC.) Stapf). A response surface methodology, i.e. a three-level Box Benhen design with three repetitions and three blocks, was applied to optimize biomass production, essential oil yield and its composition. Application rates of Glomus mosseae were 0, 1 or 2 g plant-1, vermicompost 0, 5 or 10 g plant-1 and WBL 0, 10 and 20%. The AMF had no significant effect on the variables tested, but vermicompost had a significant effect on essential oil yield and WBL on essential oil yield, myercene concentration and shoot dry weigh (p < 0.05). It was found that...
Tipo: Journal article Palavras-chave: Citral; Desirability function; Lemongrass; Myrcene; Optimization; Response surface methodology.
Ano: 2011 URL: http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0717-34582011000600005
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Environmental Policy, Technology Substitution, and Cross-Media Transfers AgEcon
Osei, Edward; Babcock, Bruce A..
We consider the implications of cross-media transfers for the analysis of environmental policy and technology substitution. We discuss welfare implications from the standpoint of society and of the firm. Society's solution is shown to lead to the least level of damage, output, and waste treatment costs.
Tipo: Working or Discussion Paper Palavras-chave: Environmental policy; Isopollution; Augmented isodamage; Isocost; Cross-media transfers; Technology substitution; Optimization; Environmental Economics and Policy.
Ano: 1996 URL: http://purl.umn.edu/18361
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ESTIMATING THE IMPORTANCE OF SHELF SPACE CONFIGURATION ON RETAILER'S PROFIT AgEcon
Roucan-Kane, Maud; Martens, Bobby J.; Preckel, Paul V..
Retail shelf space allocation remains a central issue in grocery retailing. A literature review produced many studies on retail shelf space allocation, but none which evaluated shelf space allocation using three major factors at once: space, vertical height, and price. In this study, shelf space allocation was modeled from the perspective of a retailer maximizing profit using space, vertical height, and price. Using benchmarking, the results show how shelf configuration affects consumer demand and retailer profit. Parameters for the model were based on experience-based intuition. Although the initial results are not valuable at this point, the method and results create a rationale and motivation to gather primary data. Once primary data is collected, this...
Tipo: Working or Discussion Paper Palavras-chave: Shelf space allocation; Retail; Optimization; Grocery; Elasticity; GAMS; Ketchup; Marketing; C61; L81.
Ano: 2007 URL: http://purl.umn.edu/7330
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