Axially Symmetric Steady-State Models of the Basic State for Instability and Climate Studies. Part II. Nonlinear Calculations

Burner failures are common abnormal conditions associated with industrial fired heaters. Preventing from economic loss and major equipment damages can be attained by compensating the lost heat due to burners’ failures, which can be possible by defining appropriate setpoints to rearrange the firing rates for healthy burners. In this study, artificial neural network models were developed for estimating the appropriate setpoints for the combustion control system to recover an industrial fired-heater furnace from abnormal conditions. For this purpose, based on an accurate high-order mathematical model, constrained nonlinear optimization problems were solved using the genetic algorithm. For different failure scenarios, the best possible excess firing rates for healthy burners to recover the furnace from abnormal conditions were obtained and data were recorded for training and testing stages. The performances of the developed neural steady-state models were evaluated through simulation experiments. The obtained results indicated the feasibility of the proposed technique to deal with the failures in the combustion system.

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Variable-air-volume terminal units I: Steady-state models

Building Services Engineering Research and Technology ◽

10.1177/014362449801900308 ◽

1998 ◽

Vol 19 (3) ◽

pp. 155-162 ◽

Cited By ~ 4

Author(s):

I. Khoo ◽

G.J. Levermore ◽

K.M. Letherman

Keyword(s):

Steady State ◽

Variable Air Volume ◽

Air Volume ◽

Terminal Units ◽

State Models

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Introduction to One-Dimensional Steady-State Models

Solid Fuels Combustion and Gasification - Dekker Mechanical Engineering ◽

10.1201/9781420047509-c6 ◽

2010 ◽

pp. 125-140

Keyword(s):

Steady State ◽

One Dimensional ◽

State Models

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Analyse comparative de la productivité des cheptels de petits ruminants en élevage extensif tropical : une nouvelle approche par les modèles matriciels en temps discret

Revue d’élevage et de médecine vétérinaire des pays tropicaux ◽

10.19182/remvt.9809 ◽

2001 ◽

Vol 54 (1) ◽

pp. 69 ◽

Cited By ~ 5

Author(s):

Matthieu Lesnoff ◽

Renaud Lancelot ◽

Emmanuel Tillard ◽

Bernard Faye

Keyword(s):

Steady State ◽

State Models ◽

Analyse Comparative

Une nouvelle méthode d’analyse comparative de la productivité des cheptels domestiques tropicaux est présentée ici. Cette méthode a utilisé les modèles démographiques matriciels et la méthode des modèles de production à l’équilibre (steady-state models). Les méthodes démographiques classiques utilisent des modèles à pas de temps annuel, peu adaptés pour les espèces à cycle de reproduction relativement court et dont les mises bas surviennent tout au long de l’année. Dans ce nouveau modèle, l’année a été décomposée en quinzaines. Trois apports opérationnels principaux ont été présentés. Premièrement, le pas de temps court a pu diminuer le biais dans l’estimation des paramètres démographiques (fécondité, mortalité, exploitation ou importation d’animaux). Deuxièmement, le modèle périodique a pu représenter conjointement les variations intra-annuelles et interannuelles des paramètres démographiques et d’autres paramètres comme le poids ou le prix de vente des animaux. Enfin, la méthode d’inférence proposée (utilisant le bootstrap non paramétrique) a permis de calculer des intervalles de confiance et de réaliser des tests pour comparer la productivité de cheptels différents. La méthode a été testée avec des données de terrain récoltées sur des cheptels d’ovins au Sénégal. Elle peut également être appliquée à d’autres espèces domestiques ou sauvages dans divers contextes zootechniques ou écologiques.

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Updating the steady state model of C4 photosynthesis

10.1101/2021.03.13.435281 ◽

2021 ◽

Author(s):

Susanne von Caemmerer

Keyword(s):

Steady State ◽

Electron Transport ◽

Electron Transport Rate ◽

Transport Rate ◽

Initial Slope ◽

Carboxylase Activity ◽

Quantitative Correlation ◽

Steady State Model ◽

State Models

AbstractC4 plants play a key role in world agriculture. For example, C4 crops such as maize and sorghum are major contributors to both first and third world food production and the C4 grasses sugarcane; miscanthus and switchgrass are major plant sources of bioenergy. In the challenge to manipulate and enhance C4 photosynthesis, steady state models of leaf photosynthesis provide and important tool for gas exchange analysis and thought experiments that can explore photosynthetic pathway changes. Here the C4 photosynthetic model by von Caemmerer and Furbank (1999) has been updated with new kinetic parameterisation and temperature dependencies added. The parameterisation was derived from experiments on the C4 monocot, Setaria viridis, which for the first time provides a cohesive parametrisation. Mesophyll conductance and its temperature dependence have also been included, as this is an important step in the quantitative correlation between the initial slope of the CO2 response curve of CO2 assimilation and in vitro PEP carboxylase activity. Furthermore, the equations for chloroplast electron transport have been updated to include cyclic electron transport flow and equations have been added to calculate electron transport rate from measured CO2 assimilation rates.HighlightThe C4 photosynthesis model by von Caemmerer and Furbank (1999) has been updated. It now includes temperature dependencies and equations to calculate electron transport rate from measured CO2 assimilation rates.

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The emission properties, structure and stability of ionic liquid menisci undergoing electrically assisted ion evaporation

Journal of Fluid Mechanics ◽

10.1017/jfm.2021.988 ◽

2022 ◽

Vol 933 ◽

Author(s):

Ximo Gallud ◽

Paulo C. Lozano

Keyword(s):

Ionic Liquid ◽

Steady State ◽

Ion Source ◽

Emission Region ◽

Tension Stress ◽

Liquid Temperature ◽

Axially Symmetric ◽

Current Output ◽

Hydraulic Impedance ◽

Ion Evaporation

The properties and structure of electrically stressed ionic liquid menisci experiencing ion evaporation are simulated using an electrohydrodynamic model with field-enhanced thermionic emission in steady state for an axially symmetric geometry. Solutions are explored as a function of the external background field, meniscus dimension, hydraulic impedance and liquid temperature. Statically stable solutions for emitting menisci are found to be constrained to a set of conditions: a minimum hydraulic impedance, a maximum current output and a narrow range of background fields that maximizes at menisci sizes of 0.5–3 ${\rm \mu}{\rm m}$ in radius. Static stability is lost when the electric field adjacent to the electrode that holds the meniscus corresponds to an electric pressure that exceeds twice the surface tension stress of a sphere of the same size as the meniscus. Preliminary investigations suggest this limit to be universal, therefore, independent of most ionic liquid properties, reservoir pressure, hydraulic impedance or temperature and could explain the experimentally observed bifurcation of a steady ion source into two or more emission sites. Ohmic heating near the emission region increases the liquid temperature, which is found to be important to accurately describe stability boundaries. Temperature increase does not affect the current output when the hydraulic impedance is constant. This phenomenon is thought to be due to an improved interface charge relaxation enhanced by the higher electrical conductivity. Dissipated ohmic energy is mostly conducted to the electrode wall. The higher thermal diffusivity of the wall versus the liquid, allows the ion source to run in steady state without heating.

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