Faculty Opinions recommendation of Model-free forecasting outperforms the correct mechanistic model for simulated and experimental data.

2013 ◽  
Author(s):  
Chih-hao Hsieh
Keyword(s):  
Experimental Data ◽  
Mechanistic Model ◽  
Model Free

Application of a dynamic mechanistic model of small intestinal starch digestion in the dairy cow

2002 ◽  
Vol 2002 ◽  
pp. 104-104
Author(s):  
J. A. N. Mills ◽  
E. Kebreab ◽  
L. A. Crompton ◽  
J. Dijkstra ◽  
J. France
Keyword(s):  
Experimental Data ◽  
Small Intestine ◽  
Dairy Cow ◽  
Energy Recovery ◽  
Mechanistic Model ◽  
Biological Knowledge ◽  
Dietary Energy ◽  
Starch Digestion ◽  
High Contribution ◽  
Small Intestinal

The high contribution of postruminal starch digestion (>50%) to total tract starch digestion on certain energy dense diets (Mills et al. 1999) demands that limitations to small intestinal starch digestion are identified. Therefore, a dynamic mechanistic model of the small intestine was constructed and evaluated against published experimental data for abomasal carbohydrate infusions in the dairy cow. The mechanistic structure of the model allowed the current biological knowledge to be integrated into a system capable of identifying restrictions to dietary energy recovery from postruminal starch delivery.

A New Dynamic Wettability-Alteration Model for Oil-Wet Cores During Surfactant-Solution Imbibition

SPE Journal ◽  
2013 ◽  
Vol 18 (05) ◽  
pp. 818-828 ◽  
Author(s):  
M. Hosein Kalaei ◽  
Don W. Green ◽  
G. Paul Willhite
Keyword(s):  
Experimental Data ◽  
Oil Recovery ◽  
History Matching ◽  
Mechanistic Model ◽  
Surfactant Solution ◽  
Experimental Tests ◽  
Quantitative Agreement ◽  
Wettability Alteration ◽  
Porous Rock ◽  
Surfactant Solutions

Summary Wettability modification of solid rocks with surfactants is an important process and has the potential to recover oil from reservoirs. When wettability is altered by use of surfactant solutions, capillary pressure, relative permeabilities, and residual oil saturations change wherever the porous rock is contacted by the surfactant. In this study, a mechanistic model is described in which wettability alteration is simulated by a new empirical correlation of the contact angle with surfactant concentration developed from experimental data. This model was tested against results from experimental tests in which oil was displaced from oil-wet cores by imbibition of surfactant solutions. Quantitative agreement between the simulation results of oil displacement and experimental data from the literature was obtained. Simulation of the imbibition of surfactant solution in laboratory-scale cores with the new model demonstrated that wettability alteration is a dynamic process, which plays a significant role in history matching and prediction of oil recovery from oil-wet porous media. In these simulations, the gravity force was the primary cause of the surfactant-solution invasion of the core that changed the rock wettability toward a less oil-wet state.

Effect of PTFE on Thermal Conductivity of Gas Diffusion Layers of PEM Fuel Cells

2013 ◽  
Author(s):  
Hamidreza Sadeghifar ◽  
Ned Djilali ◽  
Majid Bahrami
Keyword(s):  
Experimental Data ◽  
Thermal Conductivity ◽  
Contact Resistance ◽  
Performance Modeling ◽  
Mechanistic Model ◽  
Pem Fuel Cells ◽  
Gas Diffusion ◽  
Gas Diffusion Layers ◽  
Diffusion Layers ◽  
First Time

Through-plane thermal conductivity of 14 SIGRACET gas diffusion layers (GDLs), including series 24 & 34, as well as 25 & 35, are measured under different compressive pressures, ranging from 2 to 14 bar, at the temperature of around 60 °C. The effect of compression, PTFE loadings, and micro porous layer (MPL) on thermal conductivity of the GDLs and their contact resistance with an iron clamping surface is experimentally investigated. The contact resistance of MPL coated on GDL with the substrate of that GDL is measured for the first time in this paper. A new robust mechanistic model is presented for predicting the through-plane thermal conductivity of GDLs treated with PTFE and is successfully verified with the present experimental data. The model can predict the experimentally-observed reduction in thermal conductivity as a result of PTFE treatment and provides detailed insights on performance modeling of PEMFCs.

Utilization of Gas-Liquid Cylindrical Cyclone (GLCC©) Compact Separator for Solids Removal—Part I: Minimum Required Liquid Injection Rate

2009 ◽  
Author(s):  
R. Arismendi ◽  
L. Gomez ◽  
S. Wang ◽  
R. Mohan ◽  
O. Shoham ◽  
...  
Keyword(s):  
Experimental Data ◽  
Mechanistic Model ◽  
Injection Rate ◽  
Gas Velocity ◽  
Horizontal Section ◽  
Injection Point ◽  
Solids Transport ◽  
Liquid Injection ◽  
Injection Line ◽  
Solid Liquid

The hydrodynamic behavior of gas-liquid-solids in a modified GLCC© has been studied for the first time experimentally and theoretically. A GLCC© experimental facility has been designed, constructed and utilized to acquire data on gas-solid-liquid flow in both upstream 2-inch injection line horizontal section and in the 3-inch GLCC©. Experimental data have been acquired for the minimum gas velocity required to transport the solids up to the liquid injection point, and for the minimum liquid injection rate necessary to wet the solids and capture them in the liquid phase. The data have been acquired for 4 solid particle sizes of 5 μm, 25 μm, 50 μm and 150 μm. A mechanistic model has been developed or modified for solids transport/ separation, for the prediction of the minimum transport gas velocity, and the required minimum liquid injection rate. A comparison between the model prediction and the acquired experimental data shows good agreement. The average relative error for minimum transport gas and liquid velocities are, 4.3% and 9.55%, respectively.

Model of oxygen transport and metabolism predicts effect of hyperoxia on canine muscle oxygen uptake dynamics

2007 ◽  
Vol 103 (4) ◽  
pp. 1366-1378 ◽  
Author(s):  
Nicola Lai ◽  
Gerald M. Saidel ◽  
Bruno Grassi ◽  
L. Bruce Gladden ◽  
Marco E. Cabrera
Keyword(s):  
Experimental Data ◽  
Oxygen Uptake ◽  
Oxygen Content ◽  
Oxygen Transport ◽  
Mechanistic Model ◽  
Arterial Oxygen ◽  
Cellular Respiration ◽  
Arterial Oxygen Content ◽  
Muscle Oxygen ◽  
Muscle Oxygen Uptake

Previous studies have shown that increased oxygen delivery, via increased convection or arterial oxygen content, does not speed the dynamics of oxygen uptake, V̇o2m, in dog muscle electrically stimulated at a submaximal metabolic rate. However, the dynamics of transport and metabolic processes that occur within working muscle in situ is typically unavailable in this experimental setting. To investigate factors affecting V̇o2m dynamics at contraction onset, we combined dynamic experimental data across working muscle with a mechanistic model of oxygen transport and metabolism in muscle. The model is based on dynamic mass balances for O2, ATP, and PCr. Model equations account for changes in cellular ATPase, oxidative phosphorylation, and creatine kinase fluxes in skeletal muscle during exercise, and cellular respiration depends on [ADP] and [O2]. Model simulations were conducted at different levels of arterial oxygen content and blood flow to quantify the effects of convection and diffusion of oxygen on the regulation of cellular respiration during step transitions from rest to isometric contraction in dog gastrocnemius muscle. Simulations of arteriovenous O2 differences and V̇o2m dynamics were successfully compared with experimental data (Grassi B, Gladden LB, Samaja M, Stary CM, Hogan MC. J Appl Physiol 85: 1394–1403, 1998; and Grassi B, Gladden LB, Stary CM, Wagner PD, Hogan MC. J Appl Physiol 85: 1404–1412, 1998), thus demonstrating the validity of the model, as well as its predictive capability. The main findings of this study are: 1) the estimated dynamic response of oxygen utilization at contraction onset in muscle is faster than that of oxygen uptake; and 2) hyperoxia does not accelerate the dynamics of diffusion and consequently muscle oxygen uptake at contraction onset due to the hyperoxia-induced increase in oxygen stores. These in silico derived results cannot be obtained from experimental observations alone.

scholarly journals Aging of Human Skin: Review of a Mechanistic Model and First Experimental Data

IUBMB Life ◽  
2000 ◽  
Vol 49 (4) ◽  
pp. 259-263 ◽  
Author(s):  
Paolo U. Giacomoni, Lieve Declercq, Lieve
Keyword(s):  
Experimental Data ◽  
Human Skin ◽  
Mechanistic Model

A Mechanistic Model for Wettability Alteration by Chemically Tuned Waterflooding in Carbonate Reservoirs

SPE Journal ◽  
2015 ◽  
Vol 20 (04) ◽  
pp. 767-783 ◽  
Author(s):  
C.. Qiao ◽  
L.. Li ◽  
R.T.. T. Johns ◽  
J.. Xu
Keyword(s):  
Experimental Data ◽  
Oil Recovery ◽  
Carbonate Rocks ◽  
Reactive Transport ◽  
Mechanistic Model ◽  
Contact Angles ◽  
Carbonate Reservoirs ◽  
Wettability Alteration ◽  
Physical Parameters ◽  
Minor Effect

Summary Injection of chemically tuned brines into carbonate reservoirs has been reported to enhance oil recovery by 5–30% original oil in place (OOIP) in coreflooding experiments and field tests. One proposed mechanism for this improved oil recovery (IOR) is wettability alteration of rock from oil-wet or mixed-wet to more-water-wet conditions. Modeling of wettability-alteration experiments, however, is challenging because of the complex interactions among ions in the brine and crude oil on the solid surface. In this research, we developed a multiphase and multicomponent reactive transport model that explicitly takes into account wettability alteration from these geochemical interactions in carbonate reservoirs. Published experimental data suggest that desorption of acidic-oil components from rock surfaces make carbonate rocks more water-wet. One widely accepted mechanism is that sulfate (SO42−) replaces the adsorbed carboxylic group from the rock surface, whereas cations (Ca2+, Mg2+) decrease the oil-surface potential. In the proposed mechanistic model, we used a reaction network that captures the competitive surface reactions among carboxylic groups, cations, and sulfate. These reactions control the wetting fractions and contact angles, which subsequently determine the capillary pressure, relative permeabilities, and residual oil saturations. The developed model was first tuned with experimental data from the Stevns Klint chalk and then used to predict oil recovery for additional untuned experiments under a variety of conditions where IOR increased by as much as 30% OOIP, depending on salinity and oil acidity. The numerical results showed that an increase in sulfate concentration can lead to an IOR of more than 40% OOIP, whereas cations such as Ca2+ have a relatively minor effect on recovery (approximately 5% OOIP). Physical parameters, including the total surface area of the rock and the diffusion coefficients, control the rate of recovery, but not the final oil recovery. The simulation results further demonstrate that the optimum brine formulations for chalk are those with relatively abundant SO42− (0.096 mol/kg water), moderate concentrations of cations, and low salinity (total ionic strength of less than 0.2 mol/kg water). These findings are consistent with the experimental data reported in the literature. The new model provides a powerful tool to predict the IOR potential of chemically tuned waterflooding in carbonate reservoirs under different scenarios. To the best of our knowledge, this is the first model that explicitly and mechanistically couples multiphase flow and multicomponent surface complexation with wettability alteration and oil recovery for carbonate rocks specifically.

scholarly journals Construction of a Full-Atomic Mechanistic Model of Human Apurinic/Apyrimidinic Endonuclease APE1 for Virtual Screening of Novel Inhibitors

Acta Naturae ◽  
2012 ◽  
Vol 4 (2) ◽  
pp. 80-86
Author(s):  
I. G. Khaliullin ◽  
D. K. Nilov ◽  
I. V. Shapovalova ◽  
V. K. Švedas
Keyword(s):  
Experimental Data ◽  
Active Site ◽  
Molecular Model ◽  
Mechanistic Model ◽  
Proton Acceptor ◽  
Repair System ◽  
Amino Acid Residues ◽  
Enzyme Substrate ◽  
Oncological Diseases ◽  
Important Enzyme

A full-atomic molecular model of human apurinic/apyrimidinic endonuclease APE1, an important enzyme in the DNA repair system, has been constructed. The research consisted of hybrid quantum mechanics/ molecular mechanics modeling of the enzyme-substrate interactions, as well as calculations of the ionization states of the amino acid residues of the active site of the enzyme. The choice of the APE1 mechanism with an Asp210 residue as a proton acceptor was validated by means of a generalization of modeling and experimental data. Interactions were revealed in the active site that are of greatest significance for binding the substrate and potential APE1 inhibitors (potential co-drugs of interest in the chemo- and radiotherapy of oncological diseases).

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