Journal articles on the topic 'Hydrothermal time models'
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1
Onofri, Andrea, Paolo Benincasa, Mohsen B. Mesgaran, and Christian Ritz. "Hydrothermal-time-to-event models for seed germination." European Journal of Agronomy 101 (November 2018): 129–39. http://dx.doi.org/10.1016/j.eja.2018.08.011.
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Bloomberg, M., J. R. Sedcole, E. G. Mason, and G. Buchan. "Hydrothermal time germination models for radiata pine (Pinus radiataD. Don)." Seed Science Research 19, no. 3 (September 2009): 171–82. http://dx.doi.org/10.1017/s0960258509990031.
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AbstractThe objective of this study was to fit a hydrothermal germination model to germination data for a seedlot of radiata pine (Pinus radiataD. Don). Seeds were incubated for 50 d at constant temperatures and water potentials (T = 12.5–32.5°C, Ψ = 0 to − 1.2 MPa). Most seeds completed germination within 50 d, but for low Ψ and/or non-optimal temperatures (T < 17.5°C,T>25°C) many seeds did not complete germination. In general, germination data conformed to the hydrothermal model. Departures from the model were encountered for slow-germinating seeds at suboptimal temperatures (T ≤ 20°C). To account for these departures, two alternative hydrothermal models were fitted with an additional term for an upwards shift in seed base water potential with increasing time to germination. The alternative models more correctly predicted germination time than the original model. Similarly, reduced percentage germination at supra-optimal temperatures (T>20°C) was explained by including a term in the hydrothermal model which shifted the base water potential of seeds upwards towards zero, which in turn reduced the predicted rate that hydrothermal time would be accumulated by seeds. The rate of this upwards shift in base water potential was dependent on time to complete germination and ambient water potential as well as supra-optimal temperature.
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Graziani, Anthony, and Scott J. Steinmaus. "Hydrothermal and thermal time models for the invasive grass, Arundo donax." Aquatic Botany 90, no. 1 (January 2009): 78–84. http://dx.doi.org/10.1016/j.aquabot.2008.06.003.
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Mesgaran, M. B., H. R. Mashhadi, H. Alizadeh, J. Hunt, K. R. Young, and R. D. Cousens. "Importance of distribution function selection for hydrothermal time models of seed germination." Weed Research 53, no. 2 (January 25, 2013): 89–101. http://dx.doi.org/10.1111/wre.12008.
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Hawkins, K. K., P. S. Allen, and S. E. Meyer. "Secondary dormancy induction and release inBromus tectorumseeds: the role of temperature, water potential and hydrothermal time." Seed Science Research 27, no. 1 (January 10, 2017): 12–25. http://dx.doi.org/10.1017/s0960258516000258.
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AbstractSeeds of the winter annualBromus tectorumlose primary dormancy in summer and are poised to germinate rapidly in the autumn. If rainfall is inadequate, seeds remain ungerminated and may enter secondary dormancy under winter conditions. We quantified conditions under which seeds enter secondary dormancy in the laboratory and field and also examined whether contrastingB. tectorumgenotypes responded differently to dormancy induction cues. The study also extends previous hydrothermal time models for primary dormancy loss and germination timing inB. tectorumby using similar models to account for induction and loss of secondary dormancy. Maximum secondary dormancy was achieved in the laboratory after 4 weeks at –1.0 MPa and 5°C. Seeds in the field became increasingly dormant through exposure to temperatures and water potentials in this range, confirming laboratory results. They were released from dormancy through secondary after-ripening the following summer. Different genotypes showed contrasting responses to dormancy induction cues in both laboratory and field. To examine secondary dormancy induction and release in the field in terms of hydrothermal time parameters, we first created a model that allowed mean base water potential (Ψb(50)) to vary while holding other hydrothermal time parameters constant, as in models for primary dormancy loss under dry conditions. The second model allowed all three model parameters to vary through time, to account for changes (e.g. hydrothermal time accumulation) that could occur simultaneously with dormancy induction in imbibed seeds. Shifts in Ψb(50) could explain most changes in dormancy status for seeds retrieved from the field, except during the short period prior to dormancy induction, when hydrothermal time was accumulating. This study illustrates that hydrothermal modelling, and specifically changes in Ψb(50), can be used to characterize secondary dormancy induction and loss inB. tectorum.
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Meyer, Susan E., and Phil S. Allen. "Predicting seed dormancy loss and germination timing for Bromus tectorum in a semi-arid environment using hydrothermal time models." Seed Science Research 19, no. 4 (December 2009): 225–39. http://dx.doi.org/10.1017/s0960258509990122.
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AbstractA principal goal of seed germination modelling for wild species is to predict germination timing under fluctuating field conditions. We coupled our previously developed hydrothermal time, thermal and hydrothermal afterripening time, and hydration–dehydration models for dormancy loss and germination with field seed zone temperature and water potential measurements from early summer through autumn to develop predictions of germination timing for Bromus tectorum at a semi-arid site in north-central Utah, USA. Model predictions were tested with a validation dataset based on concomitant seed retrieval experiments in 2 years. Predictions were generally in agreement with observed field germination time courses, even though integration across multiple precipitation events was necessary. Success of the modelling effort hinged on two factors. First, we used a soil capacitance sensor that measured seed zone (5 mm soil depth) water content accurately over a wide range. Second, simulations were built using physiologically based threshold models that can incorporate differences in germination timing for multiple germination fractions and for multiple stages of dormancy loss. Our results suggest that simulation models using hydrothermal time concepts can predict field germination phenology accurately. Seeds in this study integrated their experiences in a widely fluctuating environment in a manner consistent with the assumptions of hydrothermal time. Such threshold-based models also have the advantage of generality, as these concepts can be applied to many different species, environments and weather scenarios.
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Bakhshandeh, E., and M. Jamali. "Halothermal and hydrothermal time models describe germination responses of canola seeds to ageing." Plant Biology 23, no. 4 (April 23, 2021): 621–29. http://dx.doi.org/10.1111/plb.13251.
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Goulart, Francisco A. P., Renan R. Zandoná, Maicon F. Schmitz, André R. Ulguim, André Andres, and Dirceu Agostinetto. "Modeling the Emergence of Echinochloa sp. in Flooded Rice Systems." Agronomy 10, no. 11 (November 12, 2020): 1756. http://dx.doi.org/10.3390/agronomy10111756.
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Barnyard grass (Echinochloa sp.) is one of the main rice weeds. Knowledge of its emergence can support management measures. The present study models barnyard grass emergence at different flooded rice sowing periods. Furthermore, the effectiveness of the hydrothermal time model in estimating barnyard grass emergence is analyzed. Field emergence was monitored three times a week during two sowing times (October and November) and two growing seasons (2017/18 and 2018/19), in rice sown and unsown areas. Data were converted to cumulative emergence based on total seedlings. Soil temperature and moisture data were used to determine hydrothermal time. The sowing in October led to a continuous emergence of barnyard grass, while the sowing in late November led to different emergence rates. The highest emergence rates of barnyard grass occur in the first sowing time. The hydrothermal time model is adequate to estimate barnyard grass emergence in both sowing times.
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Bloomberg, M., and M. S. Watt. "Base water potential for germination of radiata pine and buddleia seeds adjusts in response to time, seed-bed water potential and supra-optimal temperatures." NZGA: Research and Practice Series 14 (January 1, 2010): 113–18. http://dx.doi.org/10.33584/rps.14.2008.3177.
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Hydrothermal germination models are mathematical models which predict germination time of seeds for a specified seed-bed temperature (T) and water potential (Ψ). In this paper, the commonly observed decline in seed germination at supra-optimal temperatures is investigated by fitting a hydrothermal time model to germination data from two unrelated plant species (Buddleia davidii and Pinus radiata). For both these species, reduced germination rates and germination percentages above optimum temperatures (20°C and 25°C for P. radiata and B. davidii, respectively) were successfully modelled by an upward shift in the seeds' base water potential (Ψb) during germination. The upwards shift in Ψb was shown to be an asymptotic function of time to germination, but with the rate increased by higher temperatures and moister seed-bed conditions. The physiological and ecological implications of this proposed model of the observed decline in germination at supraoptimal temperatures are discussed. Keywords: hydrothermal, model, Pinus radiata, Buddleia davidii
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Grose, C. J., and J. C. Afonso. "The hydrothermal power of oceanic lithosphere." Solid Earth Discussions 7, no. 1 (March 18, 2015): 1163–207. http://dx.doi.org/10.5194/sed-7-1163-2015.
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Abstract. We have estimated the power of ventilated hydrothermal heat transport, and its spatial distribution, using a set of recently developed plate models which highlight the effects of hydrothermal circulation and thermal insulation by oceanic crust. Testing lithospheric cooling models with these two effects, we estimate that global advective heat transport is about 6.6 TW, significantly lower than previous estimates, and that the fraction of that extracted by vigorous circulation on the ridge axes (<1 Ma) is about 50% of the total, significantly higher than previous estimates. This low hydrothermal power estimate originates from the thermally insulating properties of oceanic crust in relation to the mantle. Since the crust is relatively insulating, the effective properties of the lithosphere are "crust dominated" near ridge axes (yielding lower heat flow), and gradually approach mantle values over time. Thus, cooling models with crustal insulation predict low heat flow over young seafloor, implying that the difference of modeled and measured heat flow is due to the heat transport properties of the lithosphere, in addition to ventilated hydrothermal circulation as generally accepted. These estimates may bear on important problems in the physics and chemistry of the Earth because the magnitude of hydrothermal power affects chemical exchanges between the oceans and the lithosphere, thereby affecting both thermal and chemical budgets in the oceanic crust and lithosphere, the subduction factory, and convective mantle.
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Barth, Connor W., Susan E. Meyer, Julie Beckstead, and Phil S. Allen. "Hydrothermal time models for conidial germination and mycelial growth of the seed pathogen Pyrenophora semeniperda." Fungal Biology 119, no. 8 (August 2015): 720–30. http://dx.doi.org/10.1016/j.funbio.2015.04.004.
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Lühmann, Taina, and Benjamin Wirth. "Sewage Sludge Valorization via Hydrothermal Carbonization: Optimizing Dewaterability and Phosphorus Release." Energies 13, no. 17 (August 26, 2020): 4417. http://dx.doi.org/10.3390/en13174417.
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As the use of sewage sludge as a fertilizer in agriculture is increasingly restricted in the European Union, other ways to utilize this waste stream need to be developed. Sewage sludge is an ideal input material for the process of hydrothermal carbonization, as it can convert wet biomass into a solid energy carrier with increased mechanical dewaterability. Digested sewage sludge was hydrothermally carbonized at 160–200 °C for 30–60 min with initial pH levels of 1.93–8.08 to determine optimal reaction conditions for enhanced dewaterability and phosphorus release into the liquid phase. Design of experiments was used to develop response surface models, which can be applied to optimize the process conditions. For optimal dewaterability and phosphorus release, low initial pH values (pH 1.93) and mild temperatures around 170 °C are favorable. Because holding time had no statistically relevant effect, a dependency of reaction time was investigated. Though it did not yield substantially different results, it could be included in investigations of short reaction times prospectively. Low reaction temperatures and short holding times are desirable considering economic reasons for scale-up, while the high acid consumption necessary to achieve these results is unfavorable.
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Reinhardt Piskackova, Theresa, S. Chris Reberg-Horton, Robert J. Richardson, Katie M. Jennings, and Ramon G. Leon. "Incorporating environmental factors to describe wild radish (Raphanus raphanistrum) seedling emergence and plant phenology." Weed Science 68, no. 6 (August 26, 2020): 627–38. http://dx.doi.org/10.1017/wsc.2020.64.
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AbstractWild radish (Raphanus raphanistrum L.) is a weed found globally in agricultural systems. The facultative winter annual nature of this plant and high genetic variability makes modeling its growth and phenology difficult. In the present study, R. raphanistrum natural seedbanks exhibited a biphasic pattern of emergence, with emergence peaks occurring in both fall and spring. Traditional sigmoidal models were inadequate to fit this pattern, regardless of the predictive environmental variable, and a corresponding biphasic model (sigmoidal + Weibull) was used to describe emergence based on the best parameters. Each best-fit chronological, thermal, and hydrothermal model accounted for at least 85% of the variation of the validation data. Observations on phenology progression from four cohorts were used to create a common model that described all cohorts adequately. Different phenological stages were described using chronological, thermal, hydrothermal, daylength-dependent thermal time, and daylength-dependent hydrothermal time. Integrating daylength and temperature into the models was important for predicting reproductive stages of R. raphanistrum.
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Alvarado, Veria, and Kent J. Bradford. "Hydrothermal time analysis of seed dormancy in true (botanical) potato seeds." Seed Science Research 15, no. 2 (June 2005): 77–88. http://dx.doi.org/10.1079/ssr2005198.
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As seed dormancy is released within a seed population, both the rate and percentage of germination increase progressively with increasing dose of a dormancy-breaking treatment or condition. Population-based models can account for this behaviour on the basis of shifting response thresholds as dormancy is alleviated. In particular, hydrothermal time analysis of germination sensitivity to water potential (Ψ) and temperature (T) can describe these features of seed behaviour. We used the hydrothermal time model to analyse the effects of dormancy-breaking treatments on germination of dormant true (botanical) potato (Solanum tuberosumL.) seeds (TPS). After-ripening (37°C and 4% seed moisture content) of TPS for 7 or 30 days partially or fully alleviated primary dormancy. The median base water potential required to prevent germination [Ψb(50)] decreased from –0.25 MPa in control seeds to –0.87 MPa and –1.83 MPa after 7 and 30 days of after-ripening, respectively. In contrast, the base temperature for germination (Tb) was relatively unaffected (0–3.3°C). Fluridone (50 μM), an inhibitor of abscisic acid (ABA) biosynthesis, also promoted germination of dormant TPS and lowered Ψb(50), indicating a role forde novosynthesis of ABA during dormancy maintenance. Moist chilling (3 days at 4°C) or gibberellin (100 μM) alleviated secondary dormancy and lowered Ψb(50) values from –0.08 MPa to –0.36 and –0.87 MPa, respectively. The hydrothermal time model allows quantification of dormancy levels and explains why changes in germination speed and percentage are closely correlated during dormancy alleviation.
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Grose, C. J., and J. C. Afonso. "The hydrothermal power of oceanic lithosphere." Solid Earth 6, no. 4 (October 21, 2015): 1131–55. http://dx.doi.org/10.5194/se-6-1131-2015.
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Abstract. We have estimated the power of ventilated hydrothermal heat transport, and its spatial distribution, using a set of recently developed plate models which highlight the effects of axial hydrothermal circulation and thermal insulation by oceanic crust. Testing lithospheric cooling models with these two effects, we estimate that global advective heat transport is about 6.6 TW, significantly lower than most previous estimates, and that the fraction of that extracted by vigorous circulation on the ridge axes (< 1 My old) is about 50 % of the total, significantly higher than previous estimates. These new estimates originate from the thermally insulating properties of oceanic crust in relation to the mantle. Since the crust is relatively insulating, the effective properties of the lithosphere are "crust dominated" near ridge axes (a thermal blanketing effect yielding lower heat flow) and gradually approach mantle values over time. Thus, cooling models with crustal insulation predict low heat flow over young seafloor, implying that the difference of modeled and measured heat flow is due to the heat transport properties of the lithosphere, in addition to ventilated hydrothermal circulation as generally accepted. These estimates may bear on important problems in the physics and chemistry of the Earth because the magnitude of ventilated hydrothermal power affects chemical exchanges between the oceans and the lithosphere, thereby affecting both thermal and chemical budgets in the oceanic crust and lithosphere, the subduction factory, and the convective mantle.
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Dahal, Peetambar, and Kent J. Bradford. "Hydrothermal time analysis of tomato seed germination at suboptimal temperature and reduced water potential." Seed Science Research 4, no. 2 (June 1994): 71–80. http://dx.doi.org/10.1017/s096025850000204x.
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AbstractBoth temperature (T) and water potential (ψ) have consistent and quantifiable effects on the rate and extent of seed germination (radicle emergence). Germination at suboptimal T can be characterized on the basis of thermal time, or the T in excess of a base (Tb) multiplied by the time to a given percentage germination (tg). Similarly, germination at reduced ψ can be characterized on a hydrotime basis, or the ψ in excess of a base (ψb) multiplied by tg. Within a seed population, the variation in thermal times to germination for a specific percentage (g) is based upon the normal distribution of ψb values among seeds (ψb(g)). Germination responses across a range of suboptimal T and ψ might be accounted for by a general hydrothermal time model incorporating both T and ψ components. We tested this hypothesis for tomato (Lycopersicon esculentum Mill.) seeds of two genotypes differing in germination rates and tolerance of suboptimal T and ψ. For combinations of T (10−25°C) and ψ (0 to −0.9 MPa), a general hydrothermal time model accounted for approximately 75% of the variation in times to germination within the seed populations of both genotypes, and over 96% of the variation in median germination rates. However, ψb(g) distributions were sensitive to both the T and ψ of imbibition, resulting in a poor fit of the model to specific time course data. Analysis of germination timing separately for low and high ψ ranges within a given T resulted in specific models accounting for 88−99% of the variation in individual germination times and >99% of the variation in madian germination rates. Thus, for a given T and ψ range, the hydrotime model closely matched tomato seed germination time courses. Accumulated hydrothermal time accounted well for germination rates at ψ> −0.5 MPa across suboptimal T if ψb(g) was allowed to vary with T. Germination did not show a consistent response to T at ψ < −0.5 MPa, and estimated Tb values varied over different T ranges. Generalization of the hydrothermal time model across the entire range of suboptimal T and ψ was limited by physiological adjustments of the seeds to their current environment. The hydrothermal time model detected and quantified these adjustment processes that would otherwise not be evident from inspection of germination time courses. Temperature and water potential influence the time to germination via physiological mechanisms that reciprocally interact.
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Saberali, S. F., and Z. Shirmohamadi-Aliakbarkhani. "Quantifying seed germination response of melon (Cucumis melo L.) to temperature and water potential: Thermal time, hydrotime and hydrothermal time models." South African Journal of Botany 130 (May 2020): 240–49. http://dx.doi.org/10.1016/j.sajb.2019.12.024.
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Lin, Yousheng, Xiaoqian Ma, Xiaowei Peng, and Zhaosheng Yu. "Forecasting the byproducts generated by hydrothermal carbonisation of municipal solid wastes." Waste Management & Research: The Journal for a Sustainable Circular Economy 35, no. 1 (November 25, 2016): 92–100. http://dx.doi.org/10.1177/0734242x16678063.
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The influences of temperature and residence times on the conversion and product distribution during hydrothermal carbonisation of municipal solid wastes were investigated. Analysis of variance and reaction severity were used to comprehensively analyse the experimental results. Analysis results showed both reaction temperature and residence time had varying degrees of impact on production distribution and hydrochars characteristic, while the effect of combine temperature and time was negligible. It is novel to find that the products yield was a linear function of the logarithm of the reaction ordinate. Base on comprehensive consideration, 240 °C to 260 °C and 50 min to 60 min would be the optimised reaction region to achieve relatively better economic benefits for hydrothermal carbonisation of municipal solid waste. By employing the analysis results and estimated models of high heating value and solid yield established in this article, predicting the product characteristics that have not been explored experimentally become possible.
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Gareca, Edgar E., Filip Vandelook, Milton Fernández, Martin Hermy, and Olivier Honnay. "Seed germination, hydrothermal time models and the effects of global warming on a threatened high Andean tree species." Seed Science Research 22, no. 4 (October 4, 2012): 287–98. http://dx.doi.org/10.1017/s0960258512000189.
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AbstractSeed germination is a crucial event in a plant's life cycle. Because temperature and water availability are important regulators of seed germination, this process will likely be influenced by global warming. Insight into the germination process under global warming is thus crucial, and requires the study of a wide range of water availability and temperature conditions. As hydrothermal time (HTT) models evaluate seed germination for any combination of water potential and temperature, they can be suitable to predict global warming effects on seed germination. We studied the germination characteristics of the high Andean endemic tree speciesPolylepis besseri(Rosaceae), using HTT models. We were especially interested in the potential effects of global warming on seed germination. Assembly of HTT models forP. besseriwas fairly straightforward due to the lack of a seed dormancy mechanism. The models allowed prediction ofPolylepisgermination under constant and alternating temperatures. Initially, a global warming induced increase in the field minimum and mean temperature will increaseP. besserigermination, but as maximum temperatures rise above the optimum temperature for the species, seed germination will become jeopardized. Effects of global warming on seed germination are currently considerably underexplored. HTT models prove to be useful tools to study a plant species' general germination characteristics, and how they may become affected under global warming. For the endemic mountain tree speciesP. besseri, we predict an increase, followed by a decrease of seed germination under global warming.
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Colonetti, Bruno, Erlon Cristian Finardi, and Welington de Oliveira. "A Mixed-Integer and Asynchronous Level Decomposition with Application to the Stochastic Hydrothermal Unit-Commitment Problem." Algorithms 13, no. 9 (September 18, 2020): 235. http://dx.doi.org/10.3390/a13090235.
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Independent System Operators (ISOs) worldwide face the ever-increasing challenge of coping with uncertainties, which requires sophisticated algorithms for solving unit-commitment (UC) problems of increasing complexity in less-and-less time. Hence, decomposition methods are appealing options to produce easier-to-handle problems that can hopefully return good solutions at reasonable times. When applied to two-stage stochastic models, decomposition often yields subproblems that are embarrassingly parallel. Synchronous parallel-computing techniques are applied to the decomposable subproblem and frequently result in considerable time savings. However, due to the inherent run-time differences amongst the subproblem’s optimization models, unequal equipment, and communication overheads, synchronous approaches may underuse the computing resources. Consequently, asynchronous computing constitutes a natural enhancement to existing methods. In this work, we propose a novel extension of the asynchronous level decomposition to solve stochastic hydrothermal UC problems with mixed-integer variables in the first stage. In addition, we combine this novel method with an efficient task allocation to yield an innovative algorithm that far outperforms the current state-of-the-art. We provide convergence analysis of our proposal and assess its computational performance on a testbed consisting of 54 problems from a 46-bus system. Results show that our asynchronous algorithm outperforms its synchronous counterpart in terms of wall-clock computing time in 40% of the problems, providing time savings averaging about 45%, while also reducing the standard deviation of running times over the testbed in the order of 25%.
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Masin, Roberta, Donato Loddo, Stefano Benvenuti, Stefan Otto, and Giuseppe Zanin. "Modeling Weed Emergence in Italian Maize Fields." Weed Science 60, no. 2 (June 2012): 254–59. http://dx.doi.org/10.1614/ws-d-11-00124.1.
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A hydrothermal time model was developed to simulate field emergence for three weed species in maize (common lambsquarters, johnsongrass, and velvetleaf). Models predicting weed emergence facilitate well-timed and efficient POST weed control strategies (e.g., chemical and mechanical control methods). The model, called AlertInf, was created by monitoring seedling emergence from 2002 to 2008 in field experiments at three sites located in the Veneto region in northeastern Italy. Hydrothermal time was calculated using threshold parameters of temperature and water potential for germination estimated in previous laboratory studies with seeds of populations collected in Veneto. AlertInf was validated with datasets from independent field experiments conducted in Veneto and in Tuscany (west central Italy). Model validation resulted in both sites in efficiency index values ranging from 0.96 to 0.99. AlertInf, based on parameters estimated in a single region, was able to predict the timing of emergence in several sites located at the two extremes of the Italian maize growing area.
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Grasby, Stephen E., and Ian Hutcheon. "Controls on the distribution of thermal springs in the southern Canadian Cordillera." Canadian Journal of Earth Sciences 38, no. 3 (March 1, 2001): 427–40. http://dx.doi.org/10.1139/e00-091.
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Thermal springs examined in southern British Columbia are restricted to six major Eocene or later brittle fault systems. These faults provide a high-permeability flow path that allows for deep circulation of meteoric water. The depth of circulation, and thus temperature, is largely influenced by fault plane geometry. Calculated circulation depths of up to 4.8 km are consistent with models for hydrothermal ore deposits that invoke the mixing of mineralizing fluids with sulphur-rich meteoric water at depth. Mass-flux calculations indicate that a relatively small spring (5 L/s) can transport large amounts of bacterially reduced sulphur to ore-forming depths over a short geological time scale and can easily account for the sulphur associated with PbZn deposits in the southern Canadian Cordillera. Modern thermal springs may be good analogies for the upper-crustal flow systems in hydrothermal ore deposit models.
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Coco, A., J. Gottsmann, F. Whitaker, A. Rust, G. Currenti, A. Jasim, and S. Bunney. "Numerical models for ground deformation and gravity changes during volcanic unrest: simulating the hydrothermal system dynamics of a restless caldera." Solid Earth 7, no. 2 (April 12, 2016): 557–77. http://dx.doi.org/10.5194/se-7-557-2016.
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Abstract. Ground deformation and gravity changes in restless calderas during periods of unrest can signal an impending eruption and thus must be correctly interpreted for hazard evaluation. It is critical to differentiate variation of geophysical observables related to volume and pressure changes induced by magma migration from shallow hydrothermal activity associated with hot fluids of magmatic origin rising from depth. In this paper we present a numerical model to evaluate the thermo-poroelastic response of the hydrothermal system in a caldera setting by simulating pore pressure and thermal expansion associated with deep injection of hot fluids (water and carbon dioxide). Hydrothermal fluid circulation is simulated using TOUGH2, a multicomponent multiphase simulator of fluid flows in porous media. Changes in pore pressure and temperature are then evaluated and fed into a thermo-poroelastic model (one-way coupling), which is based on a finite-difference numerical method designed for axi-symmetric problems in unbounded domains.Informed by constraints available for the Campi Flegrei caldera (Italy), a series of simulations assess the influence of fluid injection rates and mechanical properties on the hydrothermal system, uplift and gravity. Heterogeneities in hydrological and mechanical properties associated with the presence of ring faults are a key determinant of the fluid flow pattern and consequently the geophysical observables. Peaks (in absolute value) of uplift and gravity change profiles computed at the ground surface are located close to injection points (namely at the centre of the model and fault areas). Temporal evolution of the ground deformation indicates that the contribution of thermal effects to the total uplift is almost negligible with respect to the pore pressure contribution during the first years of the unrest, but increases in time and becomes dominant after a long period of the simulation. After a transient increase over the first years of unrest, gravity changes become negative and decrease monotonically towards a steady-state value.Since the physics of the investigated hydrothermal system is similar to any fluid-filled reservoir, such as oil fields or CO2 reservoirs produced by sequestration, the generic formulation of the model will allow it to be employed in monitoring and interpretation of deformation and gravity data associated with other geophysical hazards that pose a risk to human activity.
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Coco, A., J. Gottsmann, F. Whitaker, A. Rust, G. Currenti, A. Jasim, and S. Bunney. "Numerical models for ground deformation and gravity changes during volcanic unrest: simulating the hydrothermal system dynamics of an active caldera." Solid Earth Discussions 7, no. 3 (August 5, 2015): 2055–107. http://dx.doi.org/10.5194/sed-7-2055-2015.
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Abstract. Ground deformation and gravity changes in active calderas during periods of unrest can signal an impending eruption and thus must be correctly interpreted for hazard evaluation. It is critical to differentiate variation of geophysical observables related to volume and pressure changes induced by magma migration from shallow hydrothermal activity associated with hot fluids of magmatic origin rising from depth. In this paper we present a numerical model to evaluate the thermo-poroelastic response of the hydrothermal system in a caldera setting by simulating pore pressure and thermal expansion associated with deep injection of hot fluids (water and carbon dioxide). Hydrothermal fluid circulation is simulated using TOUGH2, a multicomponent multiphase simulator of fluid flows in porous media. Changes in pore pressure and temperature are then evaluated and fed into a thermo-poroelastic model (one-way coupling), which is based on a finite-difference numerical method designed for axi-symmetric problems in unbounded domains. Based on data for the Campi Flegrei caldera (Italy), a series of simulations assess the influence of fluid injection rates and mechanical properties on the hydrothermal system, uplift and gravity. Heterogeneities in hydrological and mechanical properties associated with the presence of ring faults are a key determinant of the fluid flow pattern and consequently the geophysical observables. Peaks (in absolute value) of uplift and gravity change profiles computed at the ground surface are located close to injection points (namely at the centre of the model and fault areas). Temporal evolution of the ground deformation indicates that the contribution of thermal effects to the total uplift is almost negligible with respect to the pore pressure contribution during the first years of the unrest, but increases in time and becomes dominant after a long period of the simulation. After a transient increase over the first years of unrest, gravity changes become negative and decrease monotonically towards a steady state value. Since the physics of the investigated hydrothermal system is similar to any fluid-filled reservoir, such as oil fields or CO2 reservoirs produced by sequestration, the generic formulation of the model will allow it to be employed in monitoring and interpretation of deformation and gravity data associated with other geophysical hazards that pose a risk to human activity.
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Blach, Tobias, and Markus Engelhart. "Optimizing the Hydrothermal Carbonization of Sewage Sludge—Response Surface Methodology and the Effect of Volatile Solids." Water 13, no. 9 (April 28, 2021): 1225. http://dx.doi.org/10.3390/w13091225.
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This study focuses on identifying the optimum conditions of sewage sludge hydrothermal carbonization by Box–Behnken Design and on the effects of volatile solids on heating value and on process water load. To get insight into the solid and process water characteristics, we applied the Box–Behnken Design on the hydrothermal reaction temperature (190, 220, 250 °C), reaction time (0.5, 2.25, 4 h) and pH (3.9, 5, 6.1). The response surface of the liquid phase revealed decreasing dissolved organic carbon (DOC) concentrations with increasing temperature from 9446 mg/L (190 °C) to 7402 mg/L (250 °C) at 4 h reaction time. For the same hydrothermal conditions, NH4-N concentration increased from 754 to 1230 mg/L. Reaction temperature was identified as the most important process parameter, whereas reaction time and pH had only minor effects. Moreover, linear coefficients of the models were more decisive than the interrelation and quadratic coefficients. Volatile solids (VS) of the feedstock were found to significantly influence both the load of the process water and the change in heating value of the hydrochars. Process water load increased steadily with higher VS. The heating value only increased with more than around 65–80% VS in feedstock.
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Chen, Wei, Yongxin Yang, and Biao Li. "Discussion of a Coupled Strength Attenuation Model for GFRP Composites in Hydrothermal Environments." International Journal of Polymer Science 2016 (2016): 1–6. http://dx.doi.org/10.1155/2016/4258729.
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The existing attenuation models for the durability of FRP (fiber-reinforced polymer) composites in hydrothermal environments were compared, and a new coupled strength attenuation model with a temperature parameter was proposed in this paper. A series of durability experiments on GFRP sheets in hydrothermal environments were conducted to validate the accuracy and rationality of the new model. A comparison between experimental data and the calculation results of the coupled model indicated that the new model can fit better with the experimental data and effectively reflect the convergence phenomenon in the strength attenuation of GFRP in hydrothermal environments. With a temperature parameter included, the new model can better predict the service life of GFRP composites at different aging temperatures. According to the coupled attenuation model proposed in this paper, a concept and calculation method of the slow-aging time point are put forward, which can be convenient for the evaluation and design of GFRP structures with long-term durability.
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Clay, Sharon A., Adam Davis, Anita Dille, John Lindquist, Analiza H. M. Ramirez, Christy Sprague, Graig Reicks, and Frank Forcella. "Common Sunflower Seedling Emergence across the U.S. Midwest." Weed Science 62, no. 1 (March 2014): 63–70. http://dx.doi.org/10.1614/ws-d-13-00078.1.
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Predictions of weed emergence can be used by practitioners to schedule POST weed management operations. Common sunflower seed from Kansas was used at six Midwestern U.S. sites to examine the variability that 16 climates had on common sunflower emergence. Nonlinear mixed effects models, using a flexible sigmoidal Weibull function that included thermal time, hydrothermal time, and a modified hydrothermal time (with accumulation starting from January 1 of each year), were developed to describe the emergence data. An iterative method was used to select an optimal base temperature (Tb) and base and ceiling soil matric potentials (ψband ψc) that resulted in a best-fit regional model. The most parsimonious model, based on Akaike's information criterion (AIC), resulted when Tb= 4.4 C, and ψb= −20000 kPa. Deviations among model fits for individual site years indicated a negative relationship (r= −0.75; P < 0.001) between the duration of seedling emergence and growing degree days (Tb= 10 C) from October (fall planting) to March. Thus, seeds exposed to warmer conditions from fall burial to spring emergence had longer emergence periods.
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Hay, Fiona R., Andrew Mead, and Mark Bloomberg. "Modelling seed germination in response to continuous variables: use and limitations of probit analysis and alternative approaches." Seed Science Research 24, no. 3 (July 7, 2014): 165–86. http://dx.doi.org/10.1017/s096025851400021x.
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AbstractProbit-based models relating a proportional response variable to a temporal explanatory variable, assuming that the times to response are normally distributed within the population, have been used in seed biology for describing the rate of loss of viability during seed ageing and the progress of germination over time in response to environmental signals (e.g. water, temperature). These models may be expressed as generalized linear models (GLMs) with a probit (cumulative normal distribution) link function, and, using GLM fitting procedures in current statistical software, parameters of these models are efficiently estimated while taking into account the binomial error distribution of the dependent variable. The fitted parameters can then be used to calculate the ‘traditional’ model parameters, such as the hydro- or hydrothermal time constant, the mean or median response of the seeds (e.g. mean time to death, median base water potential), and the standard deviation of the normal distribution of that response. Furthermore, through consideration of the deviance and residuals, performing model evaluation and modification can lead to improved understanding of the underlying physiological/ecological processes. However, fitting a binomial GLM is not appropriate for the cumulative count data often collected from germination studies, as successive observations are not independent, and time-to-event/survival analysis should be considered instead. This review discusses well-known probit-based models, providing advice on how to collect appropriate data and fit the models to those data, and gives an overview of alternative analysis approaches to improve understanding of the underlying mechanisms of seed dormancy and germination behaviour.
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Schutte, Brian J., Emilie E. Regnier, S. Kent Harrison, Jerron T. Schmoll, Kurt Spokas, and Frank Forcella. "A Hydrothermal Seedling Emergence Model for Giant Ragweed (Ambrosia trifida)." Weed Science 56, no. 4 (August 2008): 555–60. http://dx.doi.org/10.1614/ws-07-161.1.
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Late-season giant ragweed emergence in Ohio crop fields complicates decisions concerning the optimum time to implement control measures. Our objectives were to develop a hydrothermal time emergence model for a late-emerging biotype and validate the model in a variety of locations and burial environments. To develop the model, giant ragweed seedlings were counted and removed weekly each growing season from 2000 to 2003 in a fallow field located in west central Ohio. Weather data, soil characteristics and geographic location were used to predict soil thermal and moisture conditions with the Soil Temperature and Moisture Model (STM2). Hydrothermal time (θHT) initiated March 1 and base values were extrapolated from the literature (Tb= 2 C, ψb= −10 MPa). Cumulative percent emergence initially increased rapidly and reached 60% of maximum by late April (approximately 400 θHT), leveled off for a period in May, and increased again at a lower rate before concluding in late July (approximately 2,300 θHT). The period in May when few seedlings emerged was not subject to soil temperatures or water potentials less than the θHTbase values. The biphasic pattern of emergence was modeled with two successive Weibull models that were validated in 2005 in a tilled and a no-tillage environment and in 2006 at a separate location in a no-tillage environment. Root-mean-square values for comparing actual and model predicted cumulative emergence values ranged from 8.0 to 9.5%, indicating a high degree of accuracy. This experiment demonstrated an approach to emergence modeling that can be used to forecast emergence on a local basis according to weed biotype and easily obtainable soil and weather data.
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Masin, Roberta, Donato Loddo, Stefano Benvenuti, Maria Clara Zuin, Mario Macchia, and Giuseppe Zanin. "Temperature and Water Potential as Parameters for Modeling Weed Emergence in Central-Northern Italy." Weed Science 58, no. 3 (September 2010): 216–22. http://dx.doi.org/10.1614/ws-d-09-00066.1.
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Predicting weed emergence dynamics can help farmers to plan more effective weed control. The hydrothermal time concept has been used to model emergence as a function of temperature and water potential. Application of this concept is possible if the specific biological thresholds are known. This article provides a data set of base temperature and water potential of eight maize weeds (velvetleaf, redroot pigweed, common lambsquarters, large crabgrass, barnyardgrass, yellow foxtail, green foxtail, and johnsongrass). For five of these species, two ecotypes from two extreme regions of the predominant maize-growing area in Italy (Veneto and Tuscany), were collected and compared to check possible differences that may arise from using the same thresholds for different populations. Seedling emergence of velvetleaf and johnsongrass were modeled using three different approaches: (1) thermal time calculated assuming 5 C as base temperature for both species; (2) thermal time using the specific estimated base temperatures; and (3) hydrothermal time using the specific, estimated base temperatures and water potentials. All the species had base temperatures greater than 10 C, with the exception of velvetleaf (3.9 to 4.4 C) and common lambsquarters (2.0 to 2.6 C). All species showed a calculated base-water potential equal or up to −1.00 MPa. The thresholds of the two ecotypes were similar for all the studied species, with the exception of redroot pigweed, for which the Veneto ecotype showed a water potential lower than −0.41 MPa, whereas it was −0.62 MPa for the Tuscany ecotype. Similar thresholds have been found to be useful in hydrothermal time models covering two climatic regions where maize is grown in Italy. Furthermore, a comparison between the use of specific, estimated, and common thresholds for modeling weed emergence showed that, for a better determination of weed control timing, it is often necessary to estimate the specific thresholds.
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Allen, Phil S., and Susan E. Meyer. "Ecological aspects of seed dormancy loss." Seed Science Research 8, no. 2 (June 1998): 183–92. http://dx.doi.org/10.1017/s0960258500004098.
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AbstractAdvances in seed biology include progress in understanding the ecological significance of seed dormancy mechanisms. This knowledge is being used to make more accurate predictions of germination timing in the field. For several wild species whose seedlings establish in spring, seed populations show relevant variation that can be correlated with habitat conditions. Populations from severe winter sites, where the major risk to seedlings is frost, tend to have long chilling requirements or to germinate very slowly at low temperatures. Populations from warmer sites, where the major risk is drought, are non-dormant and germinate very rapidly under these same conditions. Seed populations from intermediate sites exhibit variation in dormancy levels, both among and within plants, which spreads germination across a considerable time period. For grasses that undergo dry after-ripening, seed dormancy loss can be successfully modelled using hydrothermal time. Dormancy loss for a seed population is associated with a progressive downward shift in the mean base water potential, i.e., the water potential below which half of the seeds will not germinate. Other parameters (hydrothermal time requirement, base temperature and standard deviation of base water potentials) tend to be constant through time. Simulation models for predicting dormancy loss in the field can be created by combining measurements of seed zone temperatures with equations that describe changes in mean base water potential as a function of temperature. Successful validation of these and other models demonstrates that equations based on laboratory data can be used to predict dormancy loss under widely fluctuating field conditions. Future progress may allow prediction of germination timing based on knowledge of intrinsic dormancy characteristics of a seed population and long-term weather patterns in the field.
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Silva, Isadora Ferreira da, José Humberto Queiroz, and José Maria Rodrigues Da Luz. "OPTIMIZATION OF HYDROTHERMAL PRETREATMENT FOR ENZYMATIC HYDROLYSIS OF BANANA PSEUDO STEM USING RESPONSE SURFACE METHODOLOGY." Fungal Territory 2, no. 4 (October 30, 2019): 32–38. http://dx.doi.org/10.36547/ft.2019.2.4.32-38.
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In this study different conditions of hydrothermal pretreatment were evaluated for conversion of banana pseudo stem to fermentable sugars. A Central Composite Design (CCD) was used to obtain regression equations in function of the following variables: solid/liquid ratio (1/10; 1/12.5; 1/15), temperature (170 °C, 190 °C, 210 °C) and reaction time (10 min, 15 min, 20 min). The cellulose digestibility improved in all conditions tested, with maximum digestibility achieved at 210 °C for 10 minutes and 1/15 of solid/liquid ratio. The Glucose yield at optimal conditions was 58.4 g/kg with an excellent recovery of cellulose of 98%. Thus, the hydrothermal pretreatment demonstrated to be an effective process in increasing cellulose concentration and producing fermentable sugar from recalcitrant lignocellulosic biomass. Furthermore, based on the design response surface methodology, an optimum condition of each pretreatment could be obtained from the statistical models built. All the variables studied influenced the enzymatic sugar release.
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Lee, Min-Gyu, Sang-Kyu Kam, and Chang-Han Lee. "Kinetic and isothermal adsorption properties of strontium and cesium ions by zeolitic materials synthesized from Jeju volcanic rocks." Environmental Engineering Research 26, no. 2 (May 19, 2020): 200127–0. http://dx.doi.org/10.4491/eer.2020.127.
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The study focused on the removal of Sr and Cs ions in aqueous solutions by zeolitic materials synthesized from Jeju volcanic rocks using a fusion/hydrothermal method. The synthesis of the zeolitic materials was carried out using the fusion/hydrothermal method to reduce crystallization time. Morphological structures of the zeolitic materials could be confirmed to be the Na-A zeolite structure and crystalline with the chamfered-edged structure. In the adsorption experiment, as the initial concentrations of the Sr and Cs ions increased, it took longer to reach adsorption equilibrium. The adsorption kinetics and isotherms of Sr and Cs ions were predicted well by the pseudo-2nd-order and Langmuir isotherm models, respectively. The maximum adsorption capacities of Sr and Cs ions by the Langmuir isotherm model were 154.8 mg/g and 144.0 mg/g, respectively. The zeolitic materials prepared in this study is considered as an effective adsorbent for removing Sr and Cs ions in aqueous solutions.
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Xia, Kai, Yongfu Guo, Qijun Shao, Qu Zan, and Renbi Bai. "Removal of Mercury (II) by EDTA-Functionalized Magnetic CoFe2O4@SiO2 Nanomaterial with Core-Shell Structure." Nanomaterials 9, no. 11 (October 29, 2019): 1532. http://dx.doi.org/10.3390/nano9111532.
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In order to reduce the difficulty and risk of operation, decrease the preparation time and improve the adsorption performance of magnetic nano-silicon adsorbent with core-shell structure, a carboxylated CoFe2O4@SiO2 was prepared by EDTA-functionalized method using a safe, mild and simple hydrothermal method. The results show that the prepared material of CoFe2O4@SiO2-EDTA has a maximum adsorption capacity of 103.3 mg/g for mercury ions (Hg(II)) at pH = 7. The adsorption process of Hg(II) is a chemical reaction involving chelation and single-layer adsorption, and follows the pseudo-second-order kinetic and Langmuir adsorption isotherm models. Moreover, the removal of Hg(II) is a spontaneous and exothermic reaction. The material characterization, before and after adsorption, shows that CoFe2O4@SiO2-EDTA has excellent recyclability, hydrothermal stability and fully biodegradable properties. To summarize, it is a potential adsorption material for removing heavy metals from aqueous solutions in practical applications.
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Romano, Davide, Alessandro Gattuso, Manfredi Longo, Cinzia Caruso, Gianluca Lazzaro, Andrea Corbo, and Francesco Italiano. "Hazard Scenarios Related to Submarine Volcanic-Hydrothermal Activity and Advanced Monitoring Strategies: A Study Case from the Panarea Volcanic Group (Aeolian Islands, Italy)." Geofluids 2019 (October 13, 2019): 1–15. http://dx.doi.org/10.1155/2019/8728720.
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Geohazards associated to submarine hydrothermal systems still represent a tricky enigma to face and solve for the scientific community. The poor knowledge of a submarine environment, the rare and scarce monitoring activities, and the expensive and sometimes complicated logistics are the main problems to deal with. The submarine low-energy explosion, which occurred last November 3, 2002, off the volcanic island of Panarea, highlighted the absence of any hazard scenario to be used to manage the volcanic crisis. The “unrest” of the volcanic activity was triggered by a sudden input of deep magmatic fluids, which caused boiling water at the sea surface with a massive CO2 release besides changes in the fluids’ geochemistry. That event dramatically pushed scientists to develop new methods to monitor the seafloor venting activity. Coupling the information from geochemical investigations and data collected during the unrest of volcanic activity, we were able to (a) develop theoretical models to gain a better insight on the submarine hydrothermal system and its relationships with the local volcanic and tectonic structures and (b) to develop a preliminary submarine volcanic hazard assessment connected to the Panarea system (Aeolian Islands). In order to mitigate the potential submarine volcanic hazard, three different scenarios are described here: (1) ordinary hydrothermal venting, (2) gas burst, and (3) volcanic eruption. The experience carried out at Panarea demonstrates that the best way to face any submarine volcanic-hydrothermal hazard is to improve the collection of data in near real-time mode by multidisciplinary seafloor observatories and to combine it with periodical sampling activity.
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Biscay, Nicolas, Lucile Henry, Tadafumi Adschiri, Masahiro Yoshimura, and Cyril Aymonier. "Behavior of Silicon Carbide Materials under Dry to Hydrothermal Conditions." Nanomaterials 11, no. 5 (May 20, 2021): 1351. http://dx.doi.org/10.3390/nano11051351.
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Silicon carbide materials are excellent candidates for high-performance applications due to their outstanding thermomechanical properties and their strong corrosion resistance. SiC materials can be processed in various forms, from nanomaterials to continuous fibers. Common applications of SiC materials include the aerospace and nuclear fields, where the material is used in severely oxidative environments. Therefore, it is important to understand the kinetics of SiC oxidation and the parameters influencing them. The first part of this review focuses on the oxidation of SiC in dry air according to the Deal and Grove model showing that the oxidation behavior of SiC depends on the temperature and the time of oxidation. The oxidation rate can also be accelerated with the presence of H2O in the system due to its diffusion through the oxide scales. Therefore, wet oxidation is studied in the second part. The third part details the effect of hydrothermal media on the SiC materials that has been explained by different models, namely Yoshimura (1986), Hirayama (1989) and Allongue (1992). The last part of this review focuses on the hydrothermal corrosion of SiC materials from an application point of view and determine whether it is beneficial (manufacturing of materials) or detrimental (use of SiC in latest nuclear reactors).
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Kapetanakis, Theodoros N., Ioannis O. Vardiambasis, Christos D. Nikolopoulos, Antonios I. Konstantaras, Trinh Kieu Trang, Duy Anh Khuong, Toshiki Tsubota, Ramazan Keyikoglu, Alireza Khataee, and Dimitrios Kalderis. "Towards Engineered Hydrochars: Application of Artificial Neural Networks in the Hydrothermal Carbonization of Sewage Sludge." Energies 14, no. 11 (May 21, 2021): 3000. http://dx.doi.org/10.3390/en14113000.
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Sewage sludge hydrochars (SSHs), which are produced by hydrothermal carbonization (HTC), offer a high calorific value to be applied as a biofuel. However, HTC is a complex processand the properties of the resulting product depend heavily on the process conditions and feedstock composition. In this work, we have applied artificial neural networks (ANNs) to contribute to the production of tailored SSHs for a specific application and with optimum properties. We collected data from the published literature covering the years 2014–2021, which was then fed into different ANN models where the input data (HTC temperature, process time, and the elemental content of hydrochars) were used to predict output parameters (higher heating value, (HHV) and solid yield (%)). The proposed ANN models were successful in accurately predicting both HHV and contents of C and H. While the model NN1 (based on C, H, O content) exhibited HHV predicting performance with R2 = 0.974, another model, NN2, was also able to predict HHV with R2 = 0.936 using only C and H as input. Moreover, the inverse model of NN3 (based on H, O content, and HHV) could predict C content with an R2 of 0.939.
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Bogossian, Jessica, Anthony I. S. Kemp, and Steffen G. Hagemann. "Linking Gold Systems to the Crust-Mantle Evolution of Archean Crust in Central Brazil." Minerals 11, no. 9 (August 30, 2021): 944. http://dx.doi.org/10.3390/min11090944.
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The Goiás Archean Block (GAB) in central Brazil is an important gold district that hosts several world-class orogenic gold deposits. A better comprehension of the crustal, tectono-magmatic, and metallogenic settings of the GAB is essential to accurately define its geological evolution, evaluate Archean crustal growth models, and target gold deposits. We present an overview of gold systems, regional whole-rock Sm-Nd analyses that have been used to constrain the geological evolution of the GAB, and augment this with new in situ zircon U-Pb and Hf-O isotope data. The orogenic gold deposits show variable host rocks, structural settings, hydrothermal alteration, and ore mineralogy, but they represent epigenetic deposits formed during the same regional hydrothermal event. The overprinting of metamorphic assemblages by ore mineralogy suggests the hydrothermal event is post-peak metamorphism. The metamorphic grade of the host rocks is predominantly greenschist, locally reaching amphibolite facies. Isotope-time trends support a Mesoarchean origin of the GAB, with ocean opening at 3000–2900 Ma, and reworking at 2800–2700 Ma. Crustal growth was dominated by subduction processes via in situ magmatic additions along lithospheric discontinuities and craton margins. This promoted a crustal architecture composed of young, juvenile intra-cratonic terranes and old, long-lived reworked crustal margins. This framework provided pathways for magmatism and fluids that drove the gold endowment of the GAB.
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Ebadi, Seyed Eshagh, Zaidon Ashaari, and Mohammad Jawaid. "Optimization and empirical modelling of physical properties of hydrothermally treated oil palm wood in different buffered media using response surface methodology." BioResources 16, no. 2 (February 8, 2021): 2385–405. http://dx.doi.org/10.15376/biores.16.2.2385-2405.
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Physical properties are one of the drawbacks of oil palm wood (OPW) and they need to be improved via an appropriate method. The response surface methodology (RSM) based on central composite design (CCD) was used to evaluate and optimize the parameters of a hydrothermal treatment and to create an empirical model of the mass loss (ML, %), equilibrium moisture content (EMC, %), and anti-swelling efficiency (ASE24h, %) responses. This study focused on the effect of hydrothermal treatment (HTT) in buffer solutions to control the destructive effects of released acids caused by the degradation of hemicellulose acetyl groups. A CCD, as the most common RSM design, was applied with three treatment factors including the buffer solutions (acidic, neutral, and alkaline with pH of 5 to 8), temperature (80 to 140 °С), time (40 to 120 min), and a total of 20 experiments. The results showed that the effect of the treatment temperature was more notable than time. The medium acidity (pH) variations in HTT can lead to the removal of extractives and starch, hemicelluloses hydrolysis, the destruction of the parenchymal cells wall, and weight loss. Based on the variance analysis, the quadratic and linear models proved to be highly significant with minimal probability values (< 0.0001). The optimum conditions predicted for the HTT were a pH of 7.3, a temperature of 112.7 °С, and a time of 109.6 min.
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Royo-Esnal, Aritz, Joel Torra, Josep Antoni Conesa, Frank Forcella, and Jordi Recasens. "Modeling the Emergence of Three Arable Bedstraw (Galium) Species." Weed Science 58, no. 1 (March 2010): 10–15. http://dx.doi.org/10.1614/ws-09-063.1.
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Multiyear field data from Spain were used to model seedling emergence for three bedstraw species (Galium) that can coexist in winter cereal fields. The relationships between cumulative emergence and both growing degree days (GDD) and hydrothermal time (HTT) in soil were analyzed as sigmoid growth functions (Weibull). Iterations of base temperature and base water potential were used to optimize the HTT scale. All species were well described with Weibull functions. Both GDD and HTT models provided good descriptions of catchweed bedstraw emergence, as its seedlings have less dependence on soil water potential than false cleavers and threehorn bedstraw, which were described best with HTT. The HTT model for catchweed bedstraw was validated successfully with independent data from the United Kingdom. The models may be useful for predicting bedstraw emergence in semiarid Mediterranean regions and elsewhere.
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Guillou-Frottier, Laurent, Hugo Duwiquet, Gaëtan Launay, Audrey Taillefer, Vincent Roche, and Gaétan Link. "On the morphology and amplitude of 2D and 3D thermal anomalies induced by buoyancy-driven flow within and around fault zones." Solid Earth 11, no. 4 (August 26, 2020): 1571–95. http://dx.doi.org/10.5194/se-11-1571-2020.
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Abstract. In the first kilometers of the subsurface, temperature anomalies due to heat conduction processes rarely exceed 20–30 ∘C. When fault zones are sufficiently permeable, fluid flow may lead to much larger thermal anomalies, as evidenced by the emergence of thermal springs or by fault-related geothermal reservoirs. Hydrothermal convection triggered by buoyancy effects creates thermal anomalies whose morphology and amplitude are not well known, especially when depth- and time-dependent permeability is considered. Exploitation of shallow thermal anomalies for heat and power production partly depends on the volume and temperature of the hydrothermal reservoir. This study presents a non-exhaustive numerical investigation of fluid flow models within and around simplified fault zones, wherein realistic fluid and rock properties are accounted for, as are appropriate boundary conditions. 2D simplified models point out relevant physical mechanisms for geological problems, such as “thermal inheritance” or pulsating plumes. When permeability is increased, the classic “finger-like” upwellings evolve towards a “bulb-like” geometry, resulting in a large volume of hot fluid at shallow depth. In simplified 3D models wherein the fault zone dip angle and fault zone thickness are varied, the anomalously hot reservoir exhibits a kilometer-sized “hot air balloon” morphology or, when permeability is depth-dependent, a “funnel-shaped” geometry. For thick faults, the number of thermal anomalies increases but not the amplitude. The largest amplitude (up to 80–90 ∘C) is obtained for vertical fault zones. At the top of a vertical, 100 m wide fault zone, temperature anomalies greater than 30 ∘C may extend laterally over more than 1 km from the fault boundary. These preliminary results should motivate further geothermal investigations of more elaborated models wherein topography and fault intersections would be accounted for.
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Davis, Adam S., Sharon Clay, John Cardina, Anita Dille, Frank Forcella, John Lindquist, and Christy Sprague. "Seed Burial Physical Environment Explains Departures from Regional Hydrothermal Model of Giant Ragweed (Ambrosia trifida) Seedling Emergence in U.S. Midwest." Weed Science 61, no. 3 (September 2013): 415–21. http://dx.doi.org/10.1614/ws-d-12-00139.1.
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Robust predictions of weed seedling emergence from the soil seedbank are needed to aid weed management. A common seed accession (Illinois) of giant ragweed was buried in replicate experimental gardens over 18 site years in Illinois, Michigan, Kansas, Nebraska, Ohio, and South Dakota to examine the importance of site and climate variability by year on seedling emergence. In a nonlinear mixed-effects modeling approach, we used a flexible sigmoidal function (Weibull) to model giant ragweed cumulative seedling emergence in relation to hydrothermal time accumulated in each site-year. An iterative search method across a range of base temperature (Tb) and base and ceiling soil matric potentials (ψband ψc) for accumulation of hydrothermal time identified optima (Tb= 4.4 C, ψb= −2,500 kPa, ψc= 0 kPa) that resulted in a parsimonious regional model. Deviations between the fits for individual site-years and the fixed effects regional model were characterized by a negative relationship between random effects for the shape parameterlrc(natural log of the rate constant, indicating the speed at which emergence progressed) and thermal time (base 10 C) during the seed burial period October through March (r= −0.51, P = 0.03). One possible implication of this result is that cold winter temperatures are required to break dormancy in giant ragweed seeds. By taking advantage of advances in statistical computing approaches, development of robust regional models now is possible for explaining arable weed seedling emergence progress across wide regions.
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MAGDALENA, Carina Pitwak, Denise Alves FUNGARO, and Patricia CUNICO. "REACTIVE AZO DYE ADSORPTION USING ZEOLITIC MATERIAL: CONTACT TIME, pH, TEMPERATURE AND EFFECT OF SALTS." Periódico Tchê Química 09, no. 17 (January 20, 2012): 48–59. http://dx.doi.org/10.52571/ptq.v9.n17.2011.48_periodico17_pgs_48_59.pdf.
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Textile effluents, when not correctly treated, cause a high impact to the environment. The synthetic dyes are used in the fibber dying process, but part of them is discarded to receiving water body. The adsorption is a technique that has been used successfully for an effective removal of color. In this work, the adsorption of reactive dye Remazol Red RB from aqueous solution using zeolite of coal ash as low cost adsorbent was studied. The zeolite was synthesized by hydrothermal treatment with NaOH solution. The effect of experimental parameters such as contact time, pH, temperature and adding salt was investigated. The kinetics studies indicated that the adsorption followed the pseudo-second-order model with correlation coefficients > 0.99. The equilibrium was reached after 360 min of contact time. The experimental data were analyzed using Langmuir and Freundlich isotherm models and the data fitted well to the Langmuir isotherm. The maximum adsorption capacity of zeolite of coal ash for Remazol Vermelho RB was 1.20 mg g-1 with adsorption efficiency between 75 and 91%. The dye adsorption was more efficient in the presence of salts.
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Moltchanova, Elena, Shirin Sharifiamina, Derrick J. Moot, Ali Shayanfar, and Mark Bloomberg. "Comparison of three different statistical approaches (non-linear least-squares regression, survival analysis and Bayesian inference) in their usefulness for estimating hydrothermal time models of seed germination." Seed Science Research 30, no. 1 (March 2020): 64–72. http://dx.doi.org/10.1017/s0960258520000082.
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AbstractHydrothermal time (HTT) models describe the time course of seed germination for a population of seeds under specific temperature and water potential conditions. The parameters of the HTT model are usually estimated using either a linear regression, non-linear least squares estimation or a generalized linear regression model. There are problems with these approaches, including loss of information, and censoring and lack of independence in the germination data. Model estimation may require optimization, and this can have a heavy computational burden. Here, we compare non-linear regression with survival and Bayesian methods, to estimate HTT models for germination of two clover species. All three methods estimated similar HTT model parameters with similar root mean squared errors. However, the Bayesian approach allowed (1) efficient estimation of model parameters without the need for computation-intensive methods and (2) easy comparison of HTT parameters for the two clover species. HTT models that accounted for a species effect were superior to those that did not. Inspection of credibility intervals and estimated posterior distributions for the Bayesian HTT model shows that it is credible that most HTT model parameters were different for the two clover species, and these differences were consistent with known biological differences between species in their germination behaviour.
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Piochi, Monica, Barbara Cantucci, Giordano Montegrossi, and Gilda Currenti. "Hydrothermal Alteration at the San Vito Area of the Campi Flegrei Geothermal System in Italy: Mineral Review and Geochemical Modeling." Minerals 11, no. 8 (July 27, 2021): 810. http://dx.doi.org/10.3390/min11080810.
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The Campi Flegrei geothermal system sets in one of the most famous and hazardous volcanic caldera in the world. The geothermal dynamics is suspected to have a crucial role in the monitored unrest phases and in the eruption triggering as well. Numerical models in the literature do not properly consider the geochemical effects of fluid-rock interaction into the hydrothermal circulation and this gap limits the wholly understanding of the dynamics. This paper focuses on fluid-rock interaction effects at the Campi Flegrei and presents relevant information requested for reactive transport simulations. In particular, we provide: (1) an extensive review of available data and new petrographic analyses of the San Vito cores rearranged in a conceptual model useful to define representative geochemical and petrophysical parameters of rock formations suitable for numerical simulations and (2) the implemented thermodynamic and kinetic data set calibrated for the San Vito 1 well area, central in the geothermal reservoir. A preliminary 0D-geochemical model, performed with a different contribution of CO2 at high (165 °C) and low (85 °C) temperatures, firstly allows reproducing the hydrothermal reactions over time of the Campanian Ignimbrite formation, the most important deposits in the case study area.
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Li, Xuli, Yue Zeng, Fangyuan Chen, Teng Wang, Yixin Li, Yuchi Chen, Haobo Hou, and Min Zhou. "Synthesis of Zeolite from Carbothermal Reduction Electrolytic Manganese Residue for the Removal of Macrolide Antibiotics from Aqueous Solution." Materials 11, no. 11 (October 30, 2018): 2133. http://dx.doi.org/10.3390/ma11112133.
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Zeolite analcime (EMANA) was synthesized through the hydrothermal method by using carbothermal reduction electrolytic manganese residue (CR-EMR). The structural properties of EMANA and CR-EMR were studied using various characterization techniques. After hydrothermal synthesis, the CR-EMR became super-microporous, and the surface area increased by 4.76 times than before. Among the various synthesized zeolites, 6 h-synthesized EMANA was selected as the best adsorbent for macrolide antibiotics in aqueous solution. The adsorption performance of EMANA on the adsorption capacity was examined by using various experimental parameters, such as contact time (0–24 h), initial concentration (50–300 mg/L), temperature (30–50 °C) and pH (3–13). The experimental results were also analyzed by the Langmuir and Freundlich adsorption models, with the latter obtaining better representation. The adsorption process could be described well by the pseudo-second-order model, even under a low concentration (50 mg/L). This result suggests that the adsorption process of macrolide antibiotics is due to chemisorption. According to the Fourier Transform infrared spectroscopy (FT-IR) results, the adsorption of zeolite was mainly due to its hydroxyl group, which played an important role during the adsorption process. Moreover, EMANA is more suitable for treatment of roxithromycin (ROX) than azithromycin (AZM), because ROX has more adsorption sites for the hydroxyl group.
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Zhao, Zhun, Zhenhua Li, Penglei Cui, Shengli Li, and Lingqian Kong. "Adsorption of Basic Brown and Chrysophenine from Water Solution by Magnesium Silicate Gel." Journal of Chemistry 2015 (2015): 1–7. http://dx.doi.org/10.1155/2015/374190.
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Noncrystalline, high surface area magnesium silicate gel was successfully prepared by hydrothermal method. Such product was characterized by BET and XRD to determine surface area 576.4 m2·g−1, average pore width 2.76 nm, and amorphous surface. The adsorption behaviors of Basic Brown and Chrysophenine on magnesium silicate gel were investigated through changing initial concentration, adsorbent dosage, solution pH, contact time, and temperature. The experimental data was analyzed by the adsorption isotherms and kinetics. The results showed the adsorption progress was fast for Basic Brown, and the adsorption equilibrium was finished in 2 h, while the adsorption equilibrium of Chrysophenine was finished in 7 h. Freundlich isotherm model and second-order kinetic models described the adsorption process very well.
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Yogeshwar, Pritam, Mira Küpper, Bülent Tezkan, Volker Rath, Duygu Kiyan, Svetlana Byrdina, José Cruz, César Andrade, and Fatima Viveiros. "Innovative boat-towed transient electromagnetics — Investigation of the Furnas volcanic lake hydrothermal system, Azores." GEOPHYSICS 85, no. 2 (March 1, 2020): E41—E56. http://dx.doi.org/10.1190/geo2019-0292.1.
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Water-covered areas may lead to gaps in surface electromagnetic surveys, causing reduced resolution and, as a consequence, increased uncertainty in derived subsurface models. We have evaluated a boat-towed floating central loop time-domain electromagnetic technique that mitigates this problem. It facilitates obtaining data with a spatial sampling density, which is rarely possible with standard instrumentation on land, and it only requires moderate logistical effort. A unique field study on a shallow volcanic lake demonstrated that this method is feasible with only a minor loss of accuracy when compared to anchored and land soundings. We found that the noise sources arising from the moving instrument and the boat engine can be neglected. The field survey was performed on the Lagoa das Furnas (São Miguel, Azores Islands, Portugal), which is located within an active volcanic area and is characterized by fumarolic fields and [Formula: see text] degassing. Thus, the associated hydrothermal system is expected to extend below the lake. However, the character, geometry, and extent of this system are unknown because of the lack of boreholes and geophysical studies. In total, 600 soundings, combining towed profiles with anchored and land-based soundings, were acquired with an aim of imaging the hydrothermal system beneath the lake down to 200 m. The results from all three types of measurements compare well and thus led to consistent 1D inversion models. The inversion results delineate a highly conductive, smectite-rich cap layer dipping below the lake away from the main fumarole zone. Near this zone, the extent of the conductor agrees well with an area of intense dispersed [Formula: see text] degassing, which appears to be controlled by at least two electrically distinctive fault zones in which the conductor is found at greater depths.
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Courtney-Davies, Liam, Cristiana L. Ciobanu, Simon R. Tapster, Nigel J. Cook, Kathy Ehrig, James L. Crowley, Max R. Verdugo-Ihl, Benjamin P. Wade, and Daniel J. Condon. "OPENING THE MAGMATIC-HYDROTHERMAL WINDOW: HIGH-PRECISION U-Pb GEOCHRONOLOGY OF THE MESOPROTEROZOIC OLYMPIC DAM Cu-U-Au-Ag DEPOSIT, SOUTH AUSTRALIA." Economic Geology 115, no. 8 (August 27, 2020): 1855–70. http://dx.doi.org/10.5382/econgeo.4772.
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Abstract Establishing timescales for iron oxide copper-gold (IOCG) deposit formation and the temporal relationships between ores and the magmatic rocks from which hydrothermal, metal-rich fluids are sourced is often dependent on low-precision data, particularly for deposits that formed during the Proterozoic. Unlike accessory minerals routinely used to track hydrothermal mineralization, iron oxides are dominant components of IOCG systems and are therefore pivotal to understanding deposit evolution. The presence of ubiquitous, magmatic-hydrothermal U-(Pb)-W-Sn-Mo–bearing zoned hematite resolves a range of geochronological issues concerning formation of the ~1.6 Ga Olympic Dam IOCG deposit, South Australia, at up to ~0.05% precision (207Pb/206Pb weighted mean; 2σ) using isotope dilution-thermal ionization mass spectrometry (ID-TIMS). Coupled with chemical abrasion-ID-TIMS zircon dates from host granite and volcanic rocks within and enclosing the ore-body, a confident magmatic-hydrothermal chronology is defined. The youngest zircon date from the granite intrusion hosting Olympic Dam indicates magmatism was occurring up until 1593.28 ± 0.26 Ma. The orebody was principally formed during a major mineralizing event following granite uplift and during cupola collapse, whereby the hematite with the oldest age is recorded in the outer shell of the deposit at 1591.27 ± 0.89 Ma, ~2 m.y. later than the youngest documented magmatic zircon. Hematite dates captured throughout major lithologies, different ore zones, and the ~2-km vertical extent of the deposit support ~2 m.y. of hydrothermal activity. New age constraints on the spatial-temporal evolution of the formation of Olympic Dam are considered with respect to a mantle to crustal continuum model. Cyclical tapping of magma reservoirs to maintain crystal mushes for extended time periods and incremental building of batholiths on the million-year scale prior to main mineralization pulses can explain the ~2-m.y. temporal window temporal window inferred from the data. Despite the challenge of reconciling such an extended window with contemporary models for porphyry deposits (≤1 m.y.), formation of Proterozoic ore deposits has been addressed at high-precision and supports the case that giant IOCG deposits may form over millions of years.
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Guo, Linghui, Jiangbo Gao, Chengyuan Hao, Linlin Zhang, Shaohong Wu, and Xiangming Xiao. "Winter Wheat Green-up Date Variation and its Diverse Response on the Hydrothermal Conditions over the North China Plain, Using MODIS Time-Series Data." Remote Sensing 11, no. 13 (July 4, 2019): 1593. http://dx.doi.org/10.3390/rs11131593.
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Vegetation phenology plays a critical role in the dynamic response of terrestrial ecosystems to climate change. However, the relationship between the phenology of winter wheat and hydrothermal factors is inadequate, especially in typical agricultural areas. In this study, the possible effects of preseason climate changes on the green-up date (GUD) of winter wheat over the North China Plain (NCP) was investigated, using the MODIS EVI 8-day time-series data from 2000 to 2015, as well as the concurrent monthly mean temperature (Tm), mean maximum (Tmax) and minimum temperature (Tmin) and total precipitation (TP) data. Firstly, we quantitatively identified the time lag effects of winter wheat GUD responses to different climatic factors; then, the major driving factors for winter wheat GUD were further explored by applying multiple linear regression models. The results showed that the time lag effects of winter wheat GUD response to climatic factors were site- and climatic parameters-dependent. Negative temperature effects with about a 3-month time lag dominated in most of the NCP, whereas positive temperature effects with a zero-month lag were most common in some of the southern parts. In comparison, total precipitation had a negative zero-month lag effect in the northern region, but two lagged months occurred in the south. Regarding the time lag effects, the explanation power of climatic factors improved relatively by up to 77%, and the explanation area increased by 41.20%. Additionally, change in winter wheat GUD was primarily determined by temperature rather than by TP, with a marked spatial heterogeneity of the Tmax and Tmin effect. Our results confirmed different time lag effects from different climatic factors on phenological processes in spring, and further suggested that both Tmax and Tmin should be considered to improve the performance of spring phenology models.