scholarly journals C-STABILITY an innovative modeling framework to leverage the continuous representation of organic matter

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Julien Sainte-Marie ◽  
Matthieu Barrandon ◽  
Laurent Saint-André ◽  
Eric Gelhaye ◽  
Francis Martin ◽  
...  
Keyword(s):  
Organic Matter ◽  
Steady State ◽  
Mathematical Structure ◽  
Continuous Representation ◽  
New Paradigm ◽  
Modeling Framework ◽  
Stability Model ◽  
Influence Of Substrate ◽  
Continuous Modeling ◽  
Theoretical Simulations

AbstractThe understanding of soil organic matter (SOM) dynamics has considerably advanced in recent years. It was previously assumed that most SOM consisted of recalcitrant compounds, whereas the emerging view considers SOM as a range of polymers continuously processed into smaller molecules by decomposer enzymes. Mainstreaming this new paradigm in current models is challenging because of their ill-adapted framework. We propose the C-STABILITY model to resolve this issue. Its innovative framework combines compartmental and continuous modeling approaches to accurately reproduce SOM cycling processes. C-STABILITY emphasizes the influence of substrate accessibility on SOM turnover and makes enzymatic and microbial biotransformations of substrate explicit. Theoretical simulations provide new insights on how depolymerization and decomposers ecology impact organic matter chemistry and amount during decomposition and at steady state. The flexible mathematical structure of C-STABILITY offers a promising foundation for exploring new mechanistic hypotheses and supporting the design of future experiments.

A study on the steady state of total organic matter in the Ocean

1970 ◽  
Vol 26 (6) ◽  
pp. 354-359 ◽  
Author(s):  
Chikayoshi Matsudaira ◽  
Keinosuke Motohashi
Keyword(s):  
Organic Matter ◽  
Steady State ◽  
Total Organic Matter

scholarly journals A Review of Concepts, Benefits, and Challenges for Future Electrical Propulsion-Based Aircraft

Aerospace ◽  
2020 ◽  
Vol 7 (4) ◽  
pp. 44 ◽  
Author(s):  
Smruti Sahoo ◽  
Xin Zhao ◽  
Konstantinos Kyprianidis
Keyword(s):  
Technological Development ◽  
Propulsion System ◽  
New Paradigm ◽  
Modeling Framework ◽  
Future Technology ◽  
Electric Aircraft ◽  
Electrical Propulsion ◽  
Development Paths ◽  
System Configurations ◽  
Insight Into

Electrification of the propulsion system has opened the door to a new paradigm of propulsion system configurations and novel aircraft designs, which was never envisioned before. Despite lofty promises, the concept must overcome the design and sizing challenges to make it realizable. A suitable modeling framework is desired in order to explore the design space at the conceptual level. A greater investment in enabling technologies, and infrastructural developments, is expected to facilitate its successful application in the market. In this review paper, several scholarly articles were surveyed to get an insight into the current landscape of research endeavors and the formulated derivations related to electric aircraft developments. The barriers and the needed future technological development paths are discussed. The paper also includes detailed assessments of the implications and other needs pertaining to future technology, regulation, certification, and infrastructure developments, in order to make the next generation electric aircraft operation commercially worthy.

scholarly journals Gyrostatic extensions of the Howard-Krishnamurti model of thermal convection with shear

2008 ◽  
Vol 15 (1) ◽  
pp. 71-79 ◽  
Author(s):  
C. Tong ◽  
A. Gluhovsky
Keyword(s):  
Energy Conservation ◽  
Model Building ◽  
Mathematical Structure ◽  
Vertical Shear ◽  
Order Model ◽  
Modeling Framework ◽  
Physical Effects ◽  
Analysis Of Dynamics ◽  
Rayleigh Benard Convection ◽  
Rayleigh Benard

Abstract. The Howard & Krishnamurti (1986) low-order model (LOM) of Rayleigh-Bénard convection with spontaneous vertical shear can be extended to incorporate various additional physical effects, such as externally forced vertical shear and magnetic field. Designing such extended LOMs so that their mathematical structure is isomorphic to those of systems of coupled gyrostats, with damping and forcing, allows for a modular approach while respecting conservation laws. Energy conservation (in the limit of no damping and forcing) prevents solutions that diverge to infinity, which are present in the original Howard & Krishnamurti LOM. The first LOM developed here (as a candidate model of transverse rolls) involves adding a new Couette mode to represent externally forced vertical shear. The second LOM is a modification of the Lantz (1995) model for magnetoconvection with shear. The modification eliminates an invariant manifold in the original model that leads to potentially unphysical behavior, namely solutions that diverge to infinity, in violation of energy conservation. This paper reports the first extension of the coupled gyrostats modeling framework to incorporate externally forced vertical shear and magnetoconvection with shear. Its aim is to demonstrate better model building techniques that avoid pathologies present in earlier models; consequently we do not focus here on analysis of dynamics or model validation.

Factors influencing the achievement of steady state in mercury contamination among lakes and catchments of south-central Ontario

2009 ◽  
Vol 66 (2) ◽  
pp. 187-200 ◽  
Author(s):  
R. Brad Mills ◽  
Andrew M. Paterson ◽  
Jules M. Blais ◽  
David R.S. Lean ◽  
John P. Smol ◽  
...  
Keyword(s):  
Organic Matter ◽  
Steady State ◽  
Annual Runoff ◽  
Model Fit ◽  
Mercury Contamination ◽  
Positive Linear Relationship ◽  
South Central ◽  
Factors Influencing ◽  
Headwater Lakes ◽  
Drainage Ratio

Mercury (Hg) concentrations in recent (0.5–1 cm) and preindustrial (>30 cm) sediments were examined across lakes in south-central and eastern Ontario, Canada (45.53°N, 82.41°W to 44.15°N, 76.25°W), to determine whether Hg exported from watersheds is at steady state with atmospheric deposition. An examination of headwater lakes revealed that Hg enrichment was not uniform among watersheds but that the enrichment factor (EF = [Hg]present day/[Hg]preindustrial, standardized for organic matter) decreased as a function of drainage ratio (Ad /Ao, watershedarea/lakearea). Furthermore, the model fit was improved after accounting for differences in sulfate concentrations and pH among lakes: EF = (Ad /Ao)–15.96 – 0.07(SO 42– ) – (3.55(pH>8.3)) (R2 = 0.458, p = 0.0001). Hg concentrations in preindustrial sediments of headwater lakes showed a positive linear relationship with drainage ratio (partial t = 4.83, p < 0.0001, n = 66) that was strengthened following an adjustment for mean annual runoff (MAR) ([Hg]preindustrial = 0.011 ± 0.002(Ad /Ao) + 0.0008 ± 0.0003(MAR) (R2 = 0.108, F[1,66] = 8.01, p = 0.006)). Our results suggest that Hg export from watersheds may be currently lagging behind atmospheric Hg deposition, in which case, Hg export would increase into the future, even as Hg deposition from the atmosphere stabilizes.

A steady-state analytical slope stability model for complex hillslopes

2008 ◽  
Vol 22 (4) ◽  
pp. 546-553 ◽  
Author(s):  
Ali Talebi ◽  
Peter A. Troch ◽  
Remko Uijlenhoet
Keyword(s):  
Steady State ◽  
Slope Stability ◽  
Stability Model

Accumulation of Organic Matter in a Series of Douglas-fir Stands

1975 ◽  
Vol 5 (4) ◽  
pp. 681-690 ◽  
Author(s):  
J. Turner ◽  
James N. Long
Keyword(s):  
Organic Matter ◽  
Steady State ◽  
Aboveground Biomass ◽  
Forest Floor ◽  
Plant Biomass ◽  
Significant Proportion ◽  
Stand Density ◽  
Douglas Fir ◽  
Density Maximum ◽  
Crown Closure

The total aboveground biomass of a series of Douglas-fir stands which are located in western Washington increased with age while the foliar biomass and total crown biomass reached a steady state of about 11 000 kg/ha at between 40 and 50 years, depending upon stand density. Maximum wood productivity occurred near the time of crown closure, but the age of crown closure varied, with denser stands reaching crown closure at a younger age. Understory aboveground biomass and returns represented a significant portion of stand organic matter before crown closure but decreased in importance as the stand increased in age. In terms of relative contribution to stand organic matter, the vascular species of the understory were supplanted by mosses during the later stages of stand development. While the understory represented a small proportion of organic matter distribution, that is, less than 5% of standing plant biomass, it was a significant proportion of total productivity (up to 17%) and an even higher proportion of organic matter that was returned to the forest floor (up to 43% of total return). The forest floor in this series of stands did not reach a steady state but continued to increase in weight. The decomposition rate appeared to decrease with age.

scholarly journals Soil moisture storage and hillslope stability

2007 ◽  
Vol 7 (5) ◽  
pp. 523-534 ◽  
Author(s):  
A. Talebi ◽  
R. Uijlenhoet ◽  
P. A. Troch
Keyword(s):  
Soil Moisture ◽  
Steady State ◽  
Slope Stability ◽  
Safety Factor ◽  
Unsaturated Zone ◽  
Soil Depth ◽  
Critical Role ◽  
Infinite Slope ◽  
Stability Model ◽  
Hillslope Stability

Abstract. Recently, we presented a steady-state analytical hillslope stability model to study rain-induced shallow landslides. This model is based on kinematic wave dynamics of saturated subsurface storage and the infinite slope stability assumption. Here we apply the model to investigate the effect of neglecting the unsaturated storage on the assessment of slope stability in the steady-state hydrology. For that purpose we extend the hydrological model to compute the soil pore pressure distribution over the entire flow domain. We also apply this model for hillslopes with non-constant soil depth to compare the stability of different hillslopes and to find the critical slip surface in hillslopes with different geometric characteristics. In order to do this, we incorporate more complex approaches to compute slope stability (Janbu's non-circular method and Bishop's simplified method) in the steady-state analytical hillslope stability model. We compare the safety factor (FS) derived from the infinite slope stability method and the more complex approach for two cases: with and without the soil moisture profile in the unsaturated zone. We apply this extended hillslope stability model to nine characteristic hillslope types with three different profile curvatures (concave, straight, convex) and three different plan shapes (convergent, parallel, divergent). Overall, we find that unsaturated zone storage does not play a critical role in determining the factor of safety for shallow and deep landslides. As a result, the effect of the unsaturated zone storage on slope stability can be neglected in the steady-state hydrology and one can assume the same bulk specific weight below and above the water table. We find that steep slopes with concave profile and convergent plan shape have the least stability. We also demonstrate that in hillslopes with non-constant soil depth (possible deep landslides), the ones with convex profiles and convergent plan shapes have slip surfaces with the minimum safety factor near the outlet region. In general, when plan shape changes from divergent to convergent, stability decreases for all length profiles. Finally, we show that the applied slope stability methods and steady-state hydrology model based on the relative saturated storage can be used safely to investigate the relation between hillslope geometry and hillslope stability.

scholarly journals Colimitation of decomposition by substrate and decomposers – a comparison of model formulations

2008 ◽  
Vol 5 (1) ◽  
pp. 163-190 ◽  
Author(s):  
T. Wutzler ◽  
M. Reichstein
Keyword(s):  
Organic Matter ◽  
Steady State ◽  
Soil Organic Matter ◽  
Priming Effect ◽  
Deep Soil ◽  
Fresh Organic Matter ◽  
Decomposition Models ◽  
Decomposer Community ◽  
Som Decomposition

Abstract. Decomposition of soil organic matter (SOM) is limited by both the available substrate and the active decomposer community. The understanding of this colimitation strongly affects the understanding of feedbacks of soil carbon to global warming and its consequences. This study compares different formulations of soil organic matter (SOM) decomposition. We compiled formulations from literature into groups according to the representation of decomposer biomass on the SOM decomposition rate a) non-explicit (substrate only), b) linear, and c) non-linear. By varying the SOM decomposition equation in a basic simplified decomposition model, we analyzed the following questions. Is the priming effect represented? Under which conditions is SOM accumulation limited? And, how does steady state SOM stocks scale with amount of fresh organic matter (FOM) litter inputs? While formulations (a) did not represent the priming effect, with formulations (b) steady state SOM stocks were independent of amount of litter input. Further, with several formulations (c) there was an offset of SOM that was not decomposed when no fresh OM was supplied. The finding that a part of the SOM is not decomposed on exhaust of FOM supply supports the hypothesis of carbon stabilization in deep soil by the absence of energy-rich fresh organic matter. Different representations of colimitation of decomposition by substrate and decomposers in SOM decomposition models resulted in qualitatively different long-term behaviour. A collaborative effort by modellers and experimentalists is required to identify appropriate and inappropriate formulations.

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