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Registros recuperados: 112
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Resilience Thinking and a Decision-Analytic Approach to Conservation: Strange Bedfellows or Essential Partners? Ecology and Society
Johnson, Fred A; United States Geological Survey; fjohnson@usgs.gov; Williams, B. Ken; The Wildlife Society; byron_ken_williams@nbs.gov; Nichols, James D; United States Geological Survey; Jim_Nichols@usgs.gov.
Tipo: Peer-Reviewed Synthesis Palavras-chave: Adaptive management; Alternative stability regime; Biodiversity; Conservation; Decision analysis; Decision science; Dynamic decisions; Modeling; Optimization; Resilience; Robust decision making; Systems; Uncertainty.
Ano: 2013
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Protocol and Practice in the Adaptive Management of Waterfowl Harvests Ecology and Society
Johnson, Fred; U.S. Fish and Wildlife Service; fred_a_johnson@fws.gov; Williams, Ken; ; byron_ken_williams@nbs.gov.
Waterfowl harvest management in North America, for all its success, historically has had several shortcomings, including a lack of well-defined objectives, a failure to account for uncertain management outcomes, and inefficient use of harvest regulations to understand the effects of management. To address these and other concerns, the U.S. Fish and Wildlife Service began implementation of adaptive harvest management in 1995. Harvest policies are now developed using a Markov decision process in which there is an explicit accounting for uncontrolled environmental variation, partial controllability of harvest, and structural uncertainty in waterfowl population dynamics. Current policies are passively adaptive, in the sense that any reduction in structural...
Tipo: Peer-Reviewed Reports Palavras-chave: Adaptive management; Harvest; Hunting regulations; Markov decision process; Migratory birds; Optimization; Uncertainty; Waterfowl..
Ano: 1999
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Fermentation optimization of maltose-binding protein fused to neutrophil-activating protein from Escherichia coli TB1 Electron. J. Biotechnol.
Lu,Jike; Song,Qi; Ji,Zhenyu; Liu,Xin; Wang,Ting; Kang,Qiaozhen.
Background The fermentation conditions of recombinant maltose-binding protein fused to neutrophil-activating protein (rMBP-NAP) of Helicobacter pylori were optimized from Escherichia coli TB1 with varying medium, inoculum age and size, time, inducer, pH and temperature in batch fermentation. Results It was revealed that the optimal conditions for the production of rMBP-NAP in shake flask were as follows: M9 medium (with 3% yeast extract powder added), inoculum age of 19 h, inoculum size of 6%, initial pH of 6.6, temperature of 37°C, and 0.7 mmoL/L IPTG inducted 21 h in a 50 mL/250 mL shake flask. The recombinant protein yield was increased from 59 to 592 mg/L after optimization. Fermentation process conducted in a 10 L fermenter with similar conditions...
Tipo: Journal article Palavras-chave: Escherichia coli; Fermentation; Optimization; Recombinant protein.
Ano: 2015 URL: http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0717-34582015000400004
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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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Nutrient optimization for production of polyhydroxybutyrate from halotolerant photosynthetic bacteria cultivated under aerobic-dark condition Electron. J. Biotechnol.
Sangkharak,Kanokphorn; Prasertsan,Poonsuk.
Three halotolerant bacterial strains; Rhodobacter sphaeroides ES16 (the wild type) and the two mutant strains of R. sphaeroides ES16, namely N20 and U7, were cultivated in glutamate-malate (GM) medium and screened for production of polyhydroxybutyrate (PHB). The mutant strains N20 and U7 were found to accumulate PHB (53.9 and 42.0% of DCW, respectively) 3.6 and 2.8 times higher than the wild type strain (19.5% of DCW), respectively. R. sphaeroides N20 were selected for studies on the effects of nutrient and environmental conditions on PHB accumulation. The optimal condition was 4 g/l acetate, 0.02 g/l (NH4)2SO4, C/N ratio of 6:1, 1.0 g/l K2HPO4, 1.0 g/l KH2PO4 and 3% NaCl with initial pH at 7.0. Under this optimal condition, the maximum PHB accumulation...
Tipo: Journal article Palavras-chave: Aerobic-dark cultivation; Optimization; PHB; Polyhydroxybutyrate; Rhodobacter sphaeroides.
Ano: 2008 URL: http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0717-34582008000300009
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Production of extracellular alkaline protease by new halotolerant alkaliphilic Bacillus sp. NPST-AK15 isolated from hyper saline soda lakes Electron. J. Biotechnol.
Ibrahim,Abdelnasser S.S; Al-Salamah,Ali A; Elbadawi,Yahya B; El-Tayeb,Mohamed A; Ibrahim,Shebl Salah Shebl.
Background Alkaline proteases are among the most important classes of industrial hydrolytic enzymes. The industrial demand for alkaline proteases with favorable properties continues to enhance the search for new enzymes. The present study focused on isolation of new alkaline producing alkaliphilic bacteria from hyper saline soda lakes and optimization of the enzyme production. Results A new potent alkaline protease producing halotolerant alkaliphilic isolate NPST-AK15 was isolated from hyper saline soda lakes, which affiliated to Bacillus sp. based on 16S rRNA gene analysis. Organic nitrogen supported enzyme production showing maximum yield using yeast extract, and as a carbon source, fructose gave maximum protease production. NPST-AK15 can grow over a...
Tipo: Journal article Palavras-chave: Alkaline protease; Alkalophiles; Bacillus sp; Fermentation; Optimization.
Ano: 2015 URL: http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0717-34582015000300015
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Thermostable lipase from a newly isolated Staphylococcus xylosus strain; process optimization and characterization using RSM and ANN Electron. J. Biotechnol.
Khoramnia,Anahita; Lai,Oi Ming; Ebrahimpour,Afshin; Tanduba,Carynn Josue; Voon,Tan Siow; Mukhlis,Suriati.
Normal feed forward back-propagation artificial neural network (ANN) and cubic backward elimination response surface methodology (RSM) were used to build a predictive model of the combined effects and optimization of culture parameters for the lipase production of a newly isolated Staphylococcus xylosus. The results demonstrated a high predictive accuracy of artificial neural network compared to response surface methodology. The optimum operating condition obtained from the ANN model was found to be at 30ºC incubation temperature, pH 7.5, 60 hrs incubation period, 1.8% inoculum size and 60 rpm agitation. The lipase production increased 3.5 fold for optimal medium. The produced enzyme was characterized biochemically and this is the first report about a...
Tipo: Journal article Palavras-chave: Artificial neural network; Characterization; Lipase; Optimization; Response surface methodology; Staphylococcus xylosus.
Ano: 2010 URL: http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0717-34582010000500015
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Application of simulated annealing in simulation and optimization of drying process of Zea mays malt REA
Benvenga,Marco A. C.; Araújo,Sidnei A. de; Librantz,André F. H.; Santana,José C. C.; Tambourgi,Elias B..
Kinetic simulation and drying process optimization of corn malt by Simulated Annealing (SA) for estimation of temperature and time parameters in order to preserve maximum amylase activity in the obtained product are presented here. Germinated corn seeds were dried at 54-76 °C in a convective dryer, with occasional measurement of moisture content and enzymatic activity. The experimental data obtained were submitted to modeling. Simulation and optimization of the drying process were made by using the SA method, a randomized improvement algorithm, analogous to the simulated annealing process. Results showed that seeds were best dried between 3h and 5h. Among the models used in this work, the kinetic model of water diffusion into corn seeds showed the best...
Tipo: Info:eu-repo/semantics/article Palavras-chave: Simulated annealing; Zea mays; Drying curves; Optimization; Simulation.
Ano: 2011 URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0100-69162011000500012
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Soybean yield maps using regular and optimized sample with different configurations by simulated annealing REA
Guedes,Luciana P. C.; Ribeiro Junior,Paulo J.; Uribe-opazo,Miguel A.; Bastiani,Fernanda de.
ABSTRACT This study aimed to compare thematic maps of soybean yield for different sampling grids, using geostatistical methods (semivariance function and kriging). The analysis was performed with soybean yield data in t ha-1 in a commercial area with regular grids with distances between points of 25x25 m, 50x50 m, 75x75 m, 100x100 m, with 549, 188, 66 and 44 sampling points respectively; and data obtained by yield monitors. Optimized sampling schemes were also generated with the algorithm called Simulated Annealing, using maximization of the overall accuracy measure as a criterion for optimization. The results showed that sample size and sample density influenced the description of the spatial distribution of soybean yield. When the sample size was...
Tipo: Info:eu-repo/semantics/article Palavras-chave: Accuracy indices; Optimization; Sampling grids; Spatial variability.
Ano: 2016 URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0100-69162016000100114
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Performance and parameterization of the algorithm Simplified Generalized Simulated Annealing Genet. Mol. Biol.
Dall'Igna Júnior,Alcino; Silva,Renato S.; Mundim,Kleber C.; Dardenne,Laurent E..
The main goal of this study is to find the most effective set of parameters for the Simplified Generalized Simulated Annealing algorithm, SGSA, when applied to distinct cost function as well as to find a possible correlation between the values of these parameters sets and some topological characteristics of the hypersurface of the respective cost function. The SGSA algorithm is an extended and simplified derivative of the GSA algorithm, a Markovian stochastic process based on Tsallis statistics that has been used in many classes of problems, in particular, in biological molecular systems optimization. In all but one of the studied cost functions, the global minimum was found in 100% of the 50 runs. For these functions the best visiting parameter, qV,...
Tipo: Info:eu-repo/semantics/article Palavras-chave: Optimization; Generalized simulated annealing.
Ano: 2004 URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S1415-47572004000400024
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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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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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Optimization of growth and bacteriocin activity of the food bioprotective Carnobacterium divergens V41 in an animal origin protein free medium ArchiMer
Brillet-viel, Anne; Pilet, Marie-france; Courcoux, Philippe; Prevost, Hervé; Leroi, Francoise.
Optimization of Carnobacterium divergens V41 growth and bacteriocin activity in a culture medium deprived of animal protein, needs for food bioprotection, was performed by using a statistical approach. In a screening experiment, twelve factors (pH, temperature, carbohydrates, NaCl, yeast extract, soy peptone, sodium acetate, ammonium citrate, magnesium sulphate, manganese sulphate, ascorbic acid and thiamine) were tested for their influence on the maximal growth and bacteriocin activity using a two-level incomplete factorial design with 192 experiments performed in microtiter plate wells. Based on results, a basic medium was developed and three variables (pH, temperature and carbohydrates concentration) were selected for a scale-up study in bioreactor. A...
Tipo: Text Palavras-chave: Optimization; Carnobacterium; Bacteriocin; Experimental design; Bioreactor; Growth; Cold-smoked salmon.
Ano: 2016 URL: https://archimer.ifremer.fr/doc/00345/45615/45236.pdf
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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: https://archimer.ifremer.fr/doc/00275/38577/37102.pdf
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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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Phytoplankton growth formulation in marine ecosystem models: Should we take into account photo-acclimation and variable stoichiometry in oligotrophic areas? ArchiMer
Ayata, S. -d.; Levy, Marina; Aumont, Olivier; Sciandra, Antoine; Sainte-marie, J.; Tagliabue, A.; Bernard, Olivier.
The aim of this study is to evaluate the consequences of accounting for variable Chl:C (chlorophyll:carbon) and C:N (carbon:nitrogen) ratios in the formulation of phytoplankton growth in biogeochemical models. We compare the qualitative behavior of a suite of phytoplankton growth formulations with increasing complexity: 1) a Redfield formulation (constant C:N ratio) without photo-acclimation (constant Chl:C ratio), 2) a Redfield formulation with diagnostic chlorophyll (variable and empirical Chl:C ratio), 3) a quota formulation (variable C:N ratio) with diagnostic chlorophyll, and 4) a quota formulation with prognostic chlorophyll (dynamic variable). These phytoplankton growth formulations are embedded in a simple marine ecosystem model in a 1D framework...
Tipo: Text Palavras-chave: Biogeochemical modeling; Phytoplankton; Photo-acclimation; Redfield ratio; Internal quota; BATS; Optimization; Micro-genetic algorithm.
Ano: 2013 URL: http://archimer.ifremer.fr/doc/00159/27071/25460.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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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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Optimal design of stiffened composite underwater hulls ArchiMer
Messager, Tanguy; Chauchot, Pierre; Bigourdan, Benoit.
This numerical study deals with the stiffened composite underwater vessel design. The structures under investigation are laminated cylinders with rigid end-closures and inter-nal circumferential and longitudinal unidirectional composite stiffeners. Structural buckling induced by the high external hydrostatic pressure is considered as the major failure risk. An optimization design tool has been developed to obtain the reinforcement definition which maximizes the limit of stability: an analytical model of cylindrical composite shell buckling has been coupled to a genetic algorithm procedure. The numerical optimization tests carried out corroborate design tendencies validated previously by experiments.
Tipo: Text Palavras-chave: Optimization; Buckling; Stiffeners; Cylinders; Composite.
Ano: 2006 URL: http://archimer.ifremer.fr/doc/2006/acte-6474.pdf
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Impact of Water Supply Limitations from Federal Decisions in South Texas AgEcon
Robinson, John R.C.; Michelsen, Ari M.; Gollehon, Noel R..
This study extends and refines a previous model and provides estimates of the economic value of water shortages from shortfalls in Mexican deliveries to the U.S. In the process, we identify and evaluate a range of crop choices, appropriate irrigation technology use, water source substitution, and other mitigation strategies used by farmers to deal with water shortages. The effects of exogenous crop price and yield risk, as well as and other structural considerations are incorporated in deriving the marginal value of irrigation water for reference drought years. Results show that South Texas farmers react to risk by diversifying their crop mix, which in turn has implications for the imputed value of water and soil resources. The derived shadow price of...
Tipo: Conference Paper or Presentation Palavras-chave: Water; Irrigation; Rio Grande; Optimization; Resource /Energy Economics and Policy.
Ano: 2005 URL: http://purl.umn.edu/19464
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