ADM1‐Based Robust Interval Observer for Anaerobic Digestion Processes     

José Luis Montiel‐Escobar  Víctor Alcaraz‐González  Hugo Oscar Méndez‐Acosta  Victor González‐Álvarez 《洁净——土壤、空气、水》2012,40(9):933-940

A robust state estimation scheme is proposed for anaerobic digestion (AD) processes to estimate key variables under the most uncertain scenarios (namely, uncertainties on the process inputs and unknown reaction and specific growth rates). This scheme combines the use of the IWA Anaerobic Digestion Model No. 1 (ADM1), the interval observer theory and a minimum number of measurements to reconstruct the unmeasured process variables within guaranteed lower and upper bounds in which they evolve. The performance of this robust estimation scheme is evaluated via numerical simulations that are carried out under actual operating conditions. It is shown that under some structural and operational conditions, the proposed robust interval observer (RIO) has the property of remaining stable in the face of uncertain process inputs, badly known kinetics and load disturbances. It is also shown that the RIO is indeed a powerful tool for the estimation of biomass (composed of seven different species) from a minimum number of measurements in a system with a total of 32 variables from which 24 correspond to state variables.  相似文献   

Isotope measurements of single ostracod valves and gastropod shells for climate reconstruction: evaluation of within-sample variability and determination of optimum sample size     

Jaime Escobar  Jason H. Curtis  Mark Brenner  David A. Hodell  Jonathan A. Holmes 《Journal of Paleolimnology》2010,43(4):921-938

Sediment cores from Lakes Punta Laguna, Chichancanab, and Petén Itzá on the Yucatan Peninsula were used to (1) investigate “within-horizon” stable isotope variability (δ¹⁸O and δ¹³C) measured on multiple, single ostracod valves and gastropod shells, (2) determine the optimum number of individuals required to infer low-frequency climate changes, and (3) evaluate the potential for using intra-sample δ¹⁸O variability in ostracod and gastropod shells as a proxy measure for high-frequency climate variability. Calculated optimum sample numbers (“n”) for δ¹⁸O and δ¹³C in the ostracod Cytheridella ilosvayi and the gastropod Pyrgophorus coronatus vary appreciably throughout the cores in all three lakes. Variability and optimum “n” values were, in most cases, larger for C. ilosvayi than for P. coronatus for δ¹⁸O measurements, whereas there was no significant difference for δ¹³C measurements. This finding may be explained by differences in the ecology and life history of the two taxa as well as contrasting modes of calcification. Individual δ¹⁸O measurements on C. ilosvayi in sediments from Lake Punta Laguna show that samples from core depths that have high mean δ¹⁸O values, indicative of low effective moisture, display lower variability, whereas samples with low mean δ¹⁸O values, reflecting times of higher effective moisture, display higher variability. Relatively dry periods were thus consistently dry, whereas relatively wet periods had both wet and dry years. This interpretation of data from the cores applies to two important periods of the late Holocene, the Maya Terminal Classic period and the Little Ice Age. δ¹⁸O variability during the ancient Maya Terminal Classic Period (ca. 910–990 AD) indicates not only the driest mean conditions in the last 3,000 years, but consistently dry climate. Variability of δ¹³C measurements in single stratigraphic layers displayed no relationship with climate conditions inferred from δ¹⁸O measurements.  相似文献   

Shallow-level differentiation of phonolitic lavas from Sumaco Volcano,Ecuador     

Jennifer?M.?GarrisonEmail authorView author&#;s OrcID profile  Kenneth?W.?W.?Sims  Gene?M.?Yogodzinski  Ricardo?D.?Escobar  Sean?Scott  Patricia?Mothes  Minard?L.?Hall  Patricio?Ramon 《Contributions to Mineralogy and Petrology》2018,173(1):6

Sumaco Volcano is located in the rear-arc of Ecuador and produces phonolitic alkaline lavas hosting a unique assemblage of minerals including haüyne and titanaugite. The most mafic lavas are picrobasalts that contain titanaugite as the primary mineral phase; the most evolved tephri-phonolite lavas contain titanaugite?+?anorthoclase?+?haüyne. Titanaugite forms at middle to deep crustal pressures, whereas haüyne is only stable at shallow depths in highly oxidizing conditions. The Sumaco mineral assemblages and geochemistry indicate that fractionation of the titanaugite- and haüyne-bearing assemblage took place over a range of pressures from 5 to 25 kbar (14–75 km), with at least 50% of differentiation taking place at shallow crustal levels. Minerals record multiple cycles of recharge and mixing accompanied by an increase in fO₂ and sulfur concentration during differentiation. Mantle-like Sr and Nd isotope values (⁸⁷Sr/⁸⁶Sr = 0.70406–0.70423; ¹⁴³Nd/¹⁴⁴Nd = 0.512880–0.512913) indicate minimal crustal assimilation. Sumaco’s unique geochemical composition is not observed in the nearby volcanoes Antisana, Pan de Azucar or El Reventador suggesting that its unique magma source is confined to this volcano. The high temperature and sulfate-saturated conditions at shallow depths suggest that magma ascends rapidly to a shallow reservoir where the majority of crystallization and recharge takes place prior to eruption. An important conclusion of this research is that Sumaco does not represent typical rear-arc subduction processes, and caution should be used when using Sumaco as an end-member to evaluate across-arc processes in the Northern Volcanic Zone.  相似文献   

Specific suspended sediment yields of the Andean rivers of Chile and their relationship to climate,slope and vegetation     

E. Pepin  S. Carretier  J. L. Guyot  F. Escobar 《水文科学杂志》2013,58(7):1190-1205

Abstract

Using daily suspended sediment and water discharge data, we calculated the current mean annual runoff and Specific Suspended Sediment Yield (SSY) for 66 mountainous and piedmont catchments in Chile. These catchments are located from the extreme north of Chile to Southern Patagonia and cover an exceptionally wide range of climates, slopes, and vegetation. The SSY ranges mainly between 0 and 700 t km^-2 year^-1 with some exceptions as high as 1780 t km^-2 year^-1. The SSY increases between the extreme north and 33°S and then decreases toward the south. Sediment and water discharge north of 33°S occur mainly during summer. Farther south the contribution of winter precipitation increases and predominates. When the SSY database is correlated with topographic, climatic and vegetation indices, it is found to correlate significantly with runoff and mean slope only. In order to concentrate on erosion processes in the mountain range, 32 mountainous catchments were selected along a strong north–south SSY gradient between 27°S and 40°S. From north to south, SSY increases strongly with runoff and then decreases, even while runoff keeps increasing. In catchments where SSY is low, although runoff is high, the mean slope is less than 40% and the vegetation cover is greater than 8%. For the other catchments, runoff variations explain 67% of the variance in sediment yields. Thus, SSY seems to be controlled by vegetation cover and slope thresholds. In addition, SSY also correlates with glacier cover. However, a correlation between SSY and seismicity, although possible, is ambiguous.

Citation Pepin, E., Carretier, S., Guyot, J. L. & Escobar, F. (2010) Specific suspended sediment yields of the Andean rivers of Chile and their relationship to climate, slope and vegetation. Hydrol. Sci. J. 55(7), 1190–1205.  相似文献