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G. M. Evans - One of the best experts on this subject based on the ideXlab platform.
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peak oil testing hubbert s Curve via theoretical modeling
Natural resources research, 2008Co-Authors: S. H. Mohr, G. M. EvansAbstract:A theoretical model of conventional oil Production has been developed. The model does not assume Hubbert’s bell Curve, an asymmetric bell Curve, or a reserve-to-Production ratio method is correct, and does not use oil Production data as an input. The theoretical model is in close agreement with actual Production data until the 1979 oil crisis, with an R 2 value of greater than 0.98. Whilst the theoretical model indicates that an ideal Production Curve is slightly asymmetric, which differs from Hubbert’s Curve, the ideal model compares well with the Hubbert model, with R 2 values in excess of 0.95. Amending the theoretical model to take into account the 1979 oil crisis, and assuming the ultimately recoverable resources are in the range of 2–3 trillion barrels, the amended model predicts conventional oil Production to peak between 2010 and 2025. The amended model, for the case when the ultimately recoverable resources is 2.2 trillion barrels, indicates that oil Production peaks in 2013.
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Peak Oil: Testing Hubbert’s Curve via Theoretical Modeling
Natural Resources Research, 2008Co-Authors: S. H. Mohr, G. M. EvansAbstract:A theoretical model of conventional oil Production has been developed. The model does not assume Hubbert’s bell Curve, an asymmetric bell Curve, or a reserve-to-Production ratio method is correct, and does not use oil Production data as an input. The theoretical model is in close agreement with actual Production data until the 1979 oil crisis, with an R ^2 value of greater than 0.98. Whilst the theoretical model indicates that an ideal Production Curve is slightly asymmetric, which differs from Hubbert’s Curve, the ideal model compares well with the Hubbert model, with R ^2 values in excess of 0.95. Amending the theoretical model to take into account the 1979 oil crisis, and assuming the ultimately recoverable resources are in the range of 2–3 trillion barrels, the amended model predicts conventional oil Production to peak between 2010 and 2025. The amended model, for the case when the ultimately recoverable resources is 2.2 trillion barrels, indicates that oil Production peaks in 2013.
S. H. Mohr - One of the best experts on this subject based on the ideXlab platform.
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peak oil testing hubbert s Curve via theoretical modeling
Natural resources research, 2008Co-Authors: S. H. Mohr, G. M. EvansAbstract:A theoretical model of conventional oil Production has been developed. The model does not assume Hubbert’s bell Curve, an asymmetric bell Curve, or a reserve-to-Production ratio method is correct, and does not use oil Production data as an input. The theoretical model is in close agreement with actual Production data until the 1979 oil crisis, with an R 2 value of greater than 0.98. Whilst the theoretical model indicates that an ideal Production Curve is slightly asymmetric, which differs from Hubbert’s Curve, the ideal model compares well with the Hubbert model, with R 2 values in excess of 0.95. Amending the theoretical model to take into account the 1979 oil crisis, and assuming the ultimately recoverable resources are in the range of 2–3 trillion barrels, the amended model predicts conventional oil Production to peak between 2010 and 2025. The amended model, for the case when the ultimately recoverable resources is 2.2 trillion barrels, indicates that oil Production peaks in 2013.
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Peak Oil: Testing Hubbert’s Curve via Theoretical Modeling
Natural Resources Research, 2008Co-Authors: S. H. Mohr, G. M. EvansAbstract:A theoretical model of conventional oil Production has been developed. The model does not assume Hubbert’s bell Curve, an asymmetric bell Curve, or a reserve-to-Production ratio method is correct, and does not use oil Production data as an input. The theoretical model is in close agreement with actual Production data until the 1979 oil crisis, with an R ^2 value of greater than 0.98. Whilst the theoretical model indicates that an ideal Production Curve is slightly asymmetric, which differs from Hubbert’s Curve, the ideal model compares well with the Hubbert model, with R ^2 values in excess of 0.95. Amending the theoretical model to take into account the 1979 oil crisis, and assuming the ultimately recoverable resources are in the range of 2–3 trillion barrels, the amended model predicts conventional oil Production to peak between 2010 and 2025. The amended model, for the case when the ultimately recoverable resources is 2.2 trillion barrels, indicates that oil Production peaks in 2013.
Danísio Prado Munari - One of the best experts on this subject based on the ideXlab platform.
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Egg Production Curve fitting using nonlinear models for selected and nonselected lines of White Leghorn hens
Poultry Science, 2012Co-Authors: Rodrigo Pelicioni Savegnago, V. A. R. Cruz, Salvador Boccaletti Ramos, S. L. Caetano, G. S. Schmidt, Mônica Corrêa Ledur, L. El Faro, Danísio Prado MunariAbstract:Egg Production Curves describe the laying patterns of hen populations over time. The objectives of this study were to fit the weekly egg Production rate of selected and nonselected lines of a White Leghorn hen population, using nonlinear and segmented polynomial models, and to study how the selection process changed the egg-laying patterns between these 2 lines. Weekly egg Production rates over 54 wk of egg Production (from 17 to 70 wk of age) were measured from 1,693 and 282 laying hens from one selected and one nonselected (control) genetic line, respectively. Six nonlinear and one segmented polynomial models were gathered from the literature to investigate whether they could be used to fit Curves for the weekly egg Production rate. The goodness of fit of the models was measured using Akaike's information criterion, mean square error, coefficient of determination, graphical analysis of the fitted Curves, and the deviations of the fitted Curves. The Logistic, Yang, Segmented Polynomial, and Grossman models presented the best goodness of fit. In this population, there were significant differences between the parameter estimates of the Curves fitted for the selected and nonselected lines, thus indicating that the effect of selection changed the shape of the egg Production Curves. The selection for egg Production was efficient in modifying the birds' egg Production Curve in this population, thus resulting in genetic gain from the 5th to the 54th week of egg laying and improved the peak egg Production and the persistence of egg laying.
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Comparison of logistic and neural network models to fit to the egg Production Curve of White Leghorn hens
Poultry Science, 2011Co-Authors: Rodrigo Pelicioni Savegnago, S. L. Caetano, G. S. Schmidt, Mônica Corrêa Ledur, B. N. Nunes, Antonio Sergio Ferraudo, Danísio Prado MunariAbstract:ABSTRACT Neural networks are capable of modeling any complex function and can be used in the poultry and animal Production areas. The aim of this study was to investigate the possibility of using neural networks on an egg Production data set and fitting models to the egg Production Curve by applying 2 approaches, one using a nonlinear logistic model and the other using 2 artificial neural network models [multilayer perceptron (MLP) and radial basis function]. Two data sets from 2 generations of a White Leghorn strain that had been selected mainly for egg Production were used. In the first data set, the mean weekly egg-laying rate was ascertained over a 54-wk egg Production period. This data set was used to adjust and test the logistic model and to train and test the neural networks. The second data set, covering 52 wk of egg Production, was used to validate the models. The mean absolute deviation, mean square error, and R2 were used to evaluate the fit of the models. The MLP neural network had the best fit in the test and validation phases. The advantage of using neural networks is that they can be fitted to any kind of data set and do not require model assumptions such as those required in the nonlinear methodology. The results confirm that MLP neural networks can be used as an alternative tool to fit to egg Production. The benefits of the MLP are the great flexibility and their lack of a priori assumptions when estimating a noisy nonlinear model.
Cavus Falamaki - One of the best experts on this subject based on the ideXlab platform.
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zero valent nano sized iron clinoptilolite modified with zero valent copper for reductive nitrate removal
Process Safety and Environmental Protection, 2013Co-Authors: Fatemeh Sada Fateminia, Cavus FalamakiAbstract:Abstract Nitrates constitute one of the main toxic contaminants of groundwater. On the other hand, groundwater may be considered anoxic (oxygen concentration less than 9 μg L −1 ). This fact justifies the use of nano zero valent metals for nitrate removal. In such conditions, zero valent metals are quite stable against oxidation due to the very low level of dissolved oxygen concentration. It has been shown that the performance of zero valent iron coated clinoptilolite zeolite for the reduction of nitrate anion in un-buffered conditions may be enhanced by coating small amounts of Cu 0 onto the freshly prepared Fe 0 /zeolite composite. An optimum loading of Cu 0 exists for which the rate of nitrate removal is maximal. For this optimal composition, the nitrite anion Production Curve with time passes through a maximum. Nitrite Production, however, is slightly higher for the Cu modified zeolite. It has been shown that the nitrate removal process is only slightly dependent on the initial solution pH. In the temperature range of 20–60 °C, the process is controlled by both the liquid phase mass transfer and intrinsic reaction rate resistances. FESEM analysis of the zero valent metal/zeolite composite showed that upon the metal reduction reaction, an egg-shell distribution of zero valent metal in the zeolite agglomerate particle is produced.
D. C. Lis - One of the best experts on this subject based on the ideXlab platform.
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Gas and dust Productions of Comet 103P/Hartley 2 from millimetre observations: Interpreting rotation-induced time variations
Icarus, 2014Co-Authors: Jérémie Boissier, D. Bockelée-morvan, Nicholas Biver, Pierre Colom, J. Crovisier, Raphael Moreno, V. Zakharov, Olivier Groussin, Laurent Jorda, D. C. LisAbstract:Comet 103P/Hartley 2 made a close approach to the Earth in October 2010. It was the target of an extensive observing campaign including ground- and orbit-based observatories and was visited by the Deep Impact spacecraft in the framework of its mission extension EPOXI. We present observations of HCN and CH_3OH emission lines conducted with the IRAM Plateau de Bure interferometer on 22–23, 28 October and 4, 5 November 2010 at 1.1, 1.9 and 3.4 mm wavelengths. The thermal emission from the dust coma and nucleus is detected simultaneously. Interferometric images with unprecedented spatial resolution of ∼100 to ∼500 km are obtained. A sine–wave like variation of the thermal continuum is observed in the 23 October data, that we associate with the nucleus thermal light Curve. The nucleus contributes up to 30–55% of the observed continuum emission. The dust thermal emission is used to measure the dust Production rate. The inferred large dust-to-gas ratio (in the range 2–6) can be explained by the unusual activity of the comet for its size, which allows decimeter size particles and large boulders to be entrained by the gas due to the small nucleus gravity. The rotational temperature of CH_3OH is measured with beam radii from ∼150 km to ∼1500 km. We attribute the increase from ∼35 K to ∼46 K with increasing beam size to radiative processes. The HCN Production rate displays strong rotation-induced temporal variations, varying from ∼0.3 × 10^(25) s^(−1) to ∼2.0 × 10^(25) s^(−1) in the 4–5 November period. The HCN Production Curve, as well as the CO_2 and H_2O Production Curves measured by EPOXI, are interpreted with a geometric model which takes into account the complex rotational state of 103P/Hartley 2 and its shape. The HCN and H_2O Production Curves are in phase, showing that these molecules have common sources. The ∼1.7 h delay, in average, of the HCN and H_2O Production Curves with respect to the CO_2 Production Curve suggests that HCN and H_2O are mainly produced by subliming icy grains. The scale length of Production of HCN is determined to be on the order of 500–1000 km, implying a mean velocity of 100–200 m s^(−1) for the icy grains producing HCN. From the time evolution of the insolation of the nucleus, we show that the CO_2 Production is modulated by the insolation of the small lobe of the nucleus. The three-cycle pattern of the Production Curves reported earlier is best explained by an overactivity of the small lobe in the longitude range 0–180°. The good correlation between the insolation of the small lobe and CO_2 Production is consistent with CO_2 being produced from small depths below the surface. The time evolution of the velocity offset of the HCN lines, as well as the displacement of the HCN photocenter in the interferometric maps, are overall consistent with this interpretation. Other localized sources of gas on the nucleus surface are also suggested.
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Gas and dust Productions of Comet 103P/Hartley 2 from millimetre observations: Interpreting rotation-induced time variations
Icarus, 2014Co-Authors: Jérémie Boissier, D. Bockelée-morvan, Nicholas Biver, Pierre Colom, J. Crovisier, Raphael Moreno, V. Zakharov, Olivier Groussin, Laurent Jorda, D. C. LisAbstract:Comet 103P/Hartley 2 made a close approach to the Earth in October 2010. It was the target of an extensive observing campaign including ground- and orbit-based observatories and was visited by the Deep Impact spacecraft in the framework of its mission extension EPOXI. We present observations of HCN and CH3OH emission lines conducted with the IRAM Plateau de Bure interferometer on 22-23, 28 October and 4, 5 November 2010 at 1.1, 1.9 and 3.4 mm wavelengths. The thermal emission from the dust coma and nucleus is detected simultaneously. Interferometric images with unprecedented spatial resolution of similar to 100 to similar to 500 km are obtained. A sine-wave like variation of the thermal continuum is observed in the 23 October data, that we associate with the nucleus thermal light Curve. The nucleus contributes up to 30-55% of the observed continuum emission. The dust thermal emission is used to measure the dust Production rate. The inferred large dust-to-gas ratio (in the range 2-6) can be explained by the unusual activity of the comet for its size, which allows decimeter size particles and large boulders to be entrained by the gas due to the small nucleus gravity. The rotational temperature of CH3OH is measured with beam radii from 150 km to 1500 km. We attribute the increase from similar to 35 K to similar to 46 K with increasing beam size to radiative processes. The HCN Production rate displays strong rotation-induced temporal variations, varying from similar to 0.3 x 10(25) s(-1) to similar to 2.0 x 10(25) s(-1) in the 4-5 November period. The HCN Production Curve, as well as the CO2 and H2O Production Curves measured by EPOXI, are interpreted with a geometric model which takes into account the complex rotational state of 103P/Hartley 2 and its shape. The HCN and H2O Production Curves are in phase, showing that these molecules have common sources. The similar to 1.7 h delay, in average, of the HCN and H2O Production Curves with respect to the CO2 Production Curve suggests that HCN and H2O are mainly produced by subliming icy grains. The scale length of Production of HCN is determined to be on the order of 500-1000 km, implying a mean velocity of 100-200 m s(-1) for the icy grains producing HCN. From the time evolution of the insolation of the nucleus, we show that the CO2 Production is modulated by the insolation of the small lobe of the nucleus. The three-cycle pattern of the Production Curves reported earlier is best explained by an overactivity of the small lobe in the longitude range 0-180 degrees. The good correlation between the insolation of the small lobe and CO2 Production is consistent with CO2 being produced from small depths below the surface. The time evolution of the velocity offset of the HCN lines, as well as the displacement of the HCN photocenter in the interferometric maps, are overall consistent with this interpretation. Other localized sources of gas on the nucleus surface are also suggested. (C) 2013 Elsevier Inc. All rights reserved.
