Transport of bromide in the Bainsvlei soil: Field experiment and deterministic/stochastic model simulation. II. Intermittent water application

Soil Research ◽  
2005 ◽  
Vol 43 (1) ◽  
pp. 81 ◽  
Author(s):  
Ketema Tilahun ◽  
J. F. Botha ◽  
A. T. P. Bennie
Keyword(s):  
Steady State ◽  
Model Simulation ◽  
Soil Core ◽  
Water Fluxes ◽  
Water Application ◽  
Concentration Data ◽  
Average Pore ◽  
Continuous Application ◽  
Average Dispersion ◽  
Tracer Experiments

Despite the fact that non-uniform soil water content and variable input water fluxes are usually encountered in the field, tracer experiments have usually been carried out under steady-state conditions. The objective of this study was to analyse solute transport in a Bainsvlei soil under intermittent water application using Br– as a tracer. Sprinkler was used to apply water on a plot 200 by 200 cm. Soil core samples were taken every 20 cm to a depth of 160 cm several times during the experiment. The soil Br– concentration data were fitted to the steady-state convection–dispersion analytical model in the CXTFIT package. The average coefficients of determination yielded by this fit (r2 = 0.810) clearly support that the data could be analysed successfully with CXTFIT. The average pore-water velocity of 1.72 cm/day and average dispersion coefficient of 26.19 cm2/day determined from this fit are lower than the fitted values of the steady-state experiments. The Br– moved slower under the intermittent application of water than in the steady case, a conclusion supported by the deeper location of Br– peaks under continuous application than intermittent application after the same amount of water is applied.

Effects of sodium intake on steady-state potassium excretion

1984 ◽  
Vol 246 (6) ◽  
pp. F772-F778 ◽  
Author(s):  
D. B. Young ◽  
T. E. Jackson ◽  
U. Tipayamontri ◽  
R. C. Scott
Keyword(s):  
Steady State ◽  
Potassium Concentration ◽  
Sodium Intake ◽  
Plasma Potassium ◽  
Potassium Excretion ◽  
Distal Nephron ◽  
Concentration Data ◽  
Potassium Intake ◽  
Independent Variable ◽  
The Relationship

The effects of changes in sodium intake on the steady-state relationship between plasma potassium concentration and potassium excretion were studied in 15 chronically adrenalectomized dogs. Throughout the experiments the dogs received aldosterone at a rate of 50 micrograms/day and methylprednisolone at 1 mg/day. The relationship between plasma potassium and steady-state potassium excretion was obtained by changing potassium intake from 10 to 30 to 100 meq/day, each level being maintained for 7-10 days. At the conclusion of each period at a given level of potassium intake, plasma potassium and excretion were measured and plotted, plasma potassium being the independent variable. Such a relationship was obtained while the dogs were on three different levels of sodium intake: 10, 100, and 200 meq/day. The curves from the data obtained at 100 and 200 meq/day sodium intake both were shifted to the left of the curve obtained at 10 meq/day (P less than 0.05), although the 100 and 200 meq/day curves were not different from each other. On the basis of these data one could predict that, at a plasma potassium concentration of 4.0 meq/liter, the animals would excrete potassium at a rate of 17 meq/day on a 10 meq/day sodium intake, 37 meq/day on a 100 meq/day sodium intake, and 47 meq/day on a 200 meq/day sodium intake. Urine flow and electrolyte concentration data are consistent with the hypothesis that the sodium intake effect on potassium excretion was mediated through increases in distal nephron flow rate and decreases in distal nephron potassium concentration.

scholarly journals Estimates of Michaelis-Menten Constants for the Two Membranes of the Brain Endothelium

1984 ◽  
Vol 4 (2) ◽  
pp. 241-249 ◽  
Author(s):  
Albert Gjedde ◽  
Ove Christensen
Keyword(s):  
Steady State ◽  
Endothelial Cell ◽  
Transport Properties ◽  
Glucose Transport ◽  
Cell Membranes ◽  
Experimental Studies ◽  
Facilitated Diffusion ◽  
Capillary Endothelial Cells ◽  
The Individual ◽  
Tracer Experiments

Tracer studies on facilitated diffusion across the blood–brain barrier lead to the calculation of Michaelis-Menten constants that describe the rate of transport. However, the barrier consists of two endothelial cell membranes, and the relevance of single Michaelis-Menten constants in relation to the two cell membranes is unknown. We have formulated a model of two endothelial cell membranes and show that the measured Michaelis-Menten constants are simple functions of the properties of the individual membranes when transport across the endothelium is rapid ( P1 > 10−6 cm s−1). We also show that the Michaelis-Menten constants determined in tracer experiments describe facilitated diffusion in the steady state only if the two membranes have similar transport properties. As an application of this observation, we have examined three experimental studies that measure glucose transport in the steady state and show that the Michaelis-Menten constants for glucose transport calculated from the tracer experiments are equal to the constants calculated from the steady-state experiments. We conclude that the luminal and abluminal membranes of brain capillary endothelial cells have equal glucose transport properties.

scholarly journals KiMoSys 2.0: an upgraded database for submitting, storing and accessing experimental data for kinetic modeling

Database ◽  
2020 ◽  
Vol 2020 ◽  
Author(s):  
Hugo Mochão ◽  
Pedro Barahona ◽  
Rafael S Costa
Keyword(s):  
Experimental Data ◽  
Metabolic Networks ◽  
Model Simulation ◽  
Web Interface ◽  
Concentration Data ◽  
Web Based ◽  
Share Data ◽  
Visualization Tools ◽  
Filter Mechanism ◽  
Machine Readable

Abstract The KiMoSys (https://kimosys.org), launched in 2014, is a public repository of published experimental data, which contains concentration data of metabolites, protein abundances and flux data. It offers a web-based interface and upload facility to share data, making it accessible in structured formats, while also integrating associated kinetic models related to the data. In addition, it also supplies tools to simplify the construction process of ODE (Ordinary Differential Equations)-based models of metabolic networks. In this release, we present an update of KiMoSys with new data and several new features, including (i) an improved web interface, (ii) a new multi-filter mechanism, (iii) introduction of data visualization tools, (iv) the addition of downloadable data in machine-readable formats, (v) an improved data submission tool, (vi) the integration of a kinetic model simulation environment and (vii) the introduction of a unique persistent identifier system. We believe that this new version will improve its role as a valuable resource for the systems biology community. Database URL:  www.kimosys.org

Design and Implementation of Tuning PID Controller using Modern Optimization Techniques for Micro-Robotics System

2021 ◽  
Vol 10 (11) ◽  
pp. 51-68
Author(s):  
Ehab S. Ghith ◽  
◽  
Mohamed Sallam ◽  
Islam S. M. Khalil ◽  
Mohamed Youssef Serry ◽  
...  
Keyword(s):  
Steady State ◽  
Optimization Problems ◽  
Model Simulation ◽  
Search Algorithm ◽  
Optimal Parameter ◽  
Fitness Function ◽  
Optimization Techniques ◽  
Control Technique ◽  
Pid Controllers ◽  
Flower Pollination Algorithm

One of the main difficult tasks in the field of micro-robotics is the process of the selection of the optimal parameters for the PID controllers. Some methods existed to solve this task and the common method used was the Ziegler and Nichols. The former method require an accurate mathematical model. This method is beneficial in linear systems, however, if the system becomes more complex or non-linear the method cannot produce accurate values to the parameters of the system. A solution proposed for this problem recently is the application of optimization techniques. There are various optimization techniques can be used to solve various optimization problems. In this paper, several optimization methods are applied to compute the optimal parameter of PID controllers. These methods are flower pollination algorithm (FPA), grey wolf optimization (GWO), sin cosine algorithm (SCA), slime mould algorithm (SMA), and sparrow search algorithm (SSA). The fitness function applied in the former optimization techniques is the integral square Time multiplied square Error (ISTES) as the performance index measure. The fitness function provides minimal rise time, minimal settling time, fast response, and no overshoot, Steady state error equal to zero, a very low transient response and a non-oscillating steady state response with excellent stabilization. The effectiveness of the proposed SSA-based controller was verified by comparisons made with FPA, GWO, SCA, SMA controllers in terms of time and frequency response. Each control technique will be applied to the identified model (simulation results) using MATLAB Simulink and the laboratory setup (experimental results) using LABVIEW software. Finally, the SSA showed the highest performance in time and frequency responses.

Performance evaluation of SBR treatment for nitrogen removal from tannery wastewater

2006 ◽  
Vol 53 (12) ◽  
pp. 275-284 ◽  
Author(s):  
S. Murat ◽  
G. Insel ◽  
N. Artan ◽  
D. Orhon
Keyword(s):  
Steady State ◽  
Nitrogen Removal ◽  
System Performance ◽  
Model Simulation ◽  
Pilot Scale ◽  
Simulation System ◽  
Nitrogen Compounds ◽  
Concentration Profiles ◽  
Steady State Operation ◽  
Wide Range

Performance of SBR treatment for nitrogen removal from tannery is evaluated for a wide range of wastewater temperature between 7 and 30 °C. A pilot-scale SBR unit fed with plain-settled wastewater is operated on site for this purpose. Effective nitrogen removal is sustained by adjustment of the sludge age from 28 to 5 days. Concentration profiles of nitrogen compounds within a selected complete SBR cycle during the steady state operation at different wastewater temperatures and sludge ages are evaluated by model simulation. System performance is also interpreted in terms of modeling and stoichiometric calculation. Additional nitrate loss was observed during aerobic period when the aeration intensity was reduced by the factor of 50%.

scholarly journals How water level management affects cladoceran assemblages in lakes lateral to a reservoir

2016 ◽  
Vol 67 (12) ◽  
pp. 1853 ◽  
Author(s):  
José Roberto Debastiani-Júnior ◽  
Marcos Gomes Nogueira
Keyword(s):  
Steady State ◽  
Water Level ◽  
Submerged Macrophytes ◽  
Tropical Reservoir ◽  
Main River ◽  
River Reservoir ◽  
Continuous Application ◽  
Water Level Management ◽  
Loss Of Diversity ◽  
The Right

This study analysed the effects of induced water level depletion for macrophyte control in a tropical reservoir on the cladoceran fauna of two differentially connected lateral lakes. One lake, Pedra Branca, is located in the right margin and has a narrow connection to the main river–reservoir channel as well as a higher proportion of submerged macrophytes. On the opposite margin is Lake Guaritá, which is shallower and has a wider connection. Samples were collected over 16 consecutive months, including periods before, during and after depletion. Both lakes showed closely related trends in depth, pH, DO, conductivity, chlorophyll, temperature, suspended matter, phosphorus, nitrogen, silicate and ammonium variation, although a wider amplitude in variation was observed in Pedra Branca. This lake also had higher cladoceran diversity and a predominance of Chydoridae, whereas Bosminidae prevailed in Guaritá. Depletion caused a reduction in richness and an increase of Bosminidae in both lakes, although this was more pronounced in Pedra Branca. The management moderately affected both lakes but continuous application of this procedure may lead to a shift in the system steady-state and a loss of diversity that could be difficult to reverse.

2D FEM Estimate of Tool Wear in Hard Cutting Operation: Tool Wear and Simulation of Hard Cutting Process under Steady State

2009 ◽  
Vol 69-70 ◽  
pp. 306-310
Author(s):  
Fu Gang Yan ◽  
Cai Xu Yue ◽  
Xian Li Liu ◽  
Yu Fu Li ◽  
Shu Yi Ji
Keyword(s):  
Steady State ◽  
Tool Wear ◽  
Model Simulation ◽  
Cutting Temperature ◽  
Cutting Process ◽  
Workpiece Material ◽  
Machined Surface ◽  
Fem Model ◽  
Fem Method ◽  
Hard Cutting

Tool wear plays an important role in cutting process research. It affects the quality of machined surface and cutting parameter to a great extent, such as cutting force, cutting temperature and cutting quiver. In order to predict tool wear in hard cutting process by using FEM method, the character of tool wear during cutting process is presented firstly, and Usui’s tool wear rate model is introduced. Then the FEM model for steady state cutting process using Abaqus is established. FEM model describes the workpiece material characteristic accurately for the process of PCBN tool cutting GCr15 by adoptiving Johnson-Cook constitutive model. Simulation results of steady cutting process offer foundation to simulate tool wear.

scholarly journals Cyclic Sprinkler Irrigation and Pre-irrigation Substrate Water Content Affect Water and N Leaching from Containers

1994 ◽  
Vol 12 (4) ◽  
pp. 198-202
Author(s):  
Nabila S. Karam ◽  
Alexander X. Niemiera
Keyword(s):  
Water Content ◽  
Irrigation System ◽  
Sprinkler Irrigation ◽  
Application Rate ◽  
N Leaching ◽  
Time Interval ◽  
Water Application ◽  
Total N ◽  
Continuous Irrigation ◽  
Continuous Application

Abstract A series of sprinkler irrigation experiments were conducted to determine the influences of water application rate (WAR), pre-irrigation substrate water content (PSWC), and cyclic irrigation on water and N leaching from container-grown plants. Prior to experiments, Marigold (Tagetes erecta L. ‘Apollo’), were glass house-grown in pine bark-filled 3.8 liter (1 gal) containers. Prior to treatment, substrate was dried via evapotranspiration (ET) to targeted PSWCs. A simulated overhead irrigation system applied the daily water allotment in a single continuous application or cyclically (multiple applications); in most cases the respective ET volumes were applied to the substrate. Water application efficiency (WAE; water vol retained in substrate + water vol applied to substrate) was determined, and in some experiments, leachates were analyzed for EC, NO3-N and NH4-N. A negative linear relationship existed between WAR and WAE. Leachate NO3-N and NH4-N concentrations were unaffected by WAR, however, total N leached increased with increasing WAR. WAE of cyclic irrigation was 4% higher (absolute basis) than with continuous irrigation; WAE increased as the time interval between cyclic applications increased from 20 to 60 min. Regardless of how water was applied, WAE was inversely related to PSWC and application volume. These experiments showed that the most effective method to increase WAE is to irrigate at relatively low PSWCs; if irrigation occurs at relatively high PSWCs, then relatively low volumes should be applied.

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